Internet Engineering Task Force I. Butcher/Pingtel
Internet Draft S. Lass/MCI
draft-sinnreich-sipdev-req-03.txt D. Petrie/Pingtel
February 2004 H. Sinnreich/MCI - editor
C. Stredicke/snom
SIP Telephony Device Requirements, Configuration and Data
STATUS OF THIS MEMO
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1].
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Abstract
This informational I-D describes the requirements for SIP telephony
devices, based on the deployment experience of large numbers of SIP
phones and PC clients using different implementations. The document
reviews the generic requirements for SIP telephony devices, the
automatic device configuration process, device configuration data
and examples for XML configuration data formats.
SIP telephony devices are highly complex IP endpoints that speak
many Internet protocols, have text, audio and visual interfaces,
various input modes, and require functionality targeted at several
constituencies: (1) End users, (2) service providers and network
administrators and (3) manufacturers and system integrators.
The objectives of the requirements are a minimum set of
interoperability and multi-vendor supported core features, so as to
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SIP Telephony Device Requirements February 2004
enable similar ease of purchase, installation and operation as found
for standard PCs, analog feature phones or mobile phones.
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [2].
Table of Contents
1. Introduction...................................................3
2. Generic Requirements...........................................4
2.1 Link Layer Requirements....................................4
2.2 IP Requirements............................................5
2.3 SIP Transport Requirements.................................5
2.4 SIP User Agent Services....................................5
2.5 Support for SIP Services..................................11
2.6 SIP and Other Related Protocols...........................12
2.7 SIP Security..............................................13
2.8 Voice Codecs..............................................13
2.9 Voice-Telephony Requirements..............................15
2.10 International Requirements...............................16
2.11 Support for Applications.................................16
2.12 Web-based Feature Management.............................16
2.13 Firmware Update..........................................17
2.14 Firewall/NAT Traversal...................................17
2.15 Device Interfaces........................................18
3. Automatic Configuration.......................................19
4. Configuration Settings........................................19
4.1 Device ID.................................................20
4.2 Network Related Settings..................................20
4.3 Address Completion........................................21
4.4 Audio.....................................................22
4.5 Local and Regional Parameters.............................23
4.6 Inbound authentication....................................24
4.7 Voice mail settings.......................................24
4.8 Phonebook and Call History................................24
4.9 User Related Settings and Roaming.........................25
4.10 Line Related Settings....................................26
4.11 Line Identification......................................26
4.12 Maximum connections......................................26
5. Examples of Configuration Data................................26
5.1. Requirements for Configuration Data Representation.......27
5.2 Configuration Data Format.................................27
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5.3 Format Definition.........................................28
5.4 Handling of Unrecognized Element Names....................28
5.5 XML Configuration Data....................................28
5.6 Device settings...........................................28
5.7 User settings.............................................30
6. IANA Considerations...........................................31
7. Configuration Security........................................32
8. Changes.......................................................33
8.1 Changes since draft-sinnreich-sipdev-req-01...............33
9. Acknowledgements..............................................33
10. Authors Addresses............................................33
11. References...................................................34
11. Full Copyright Statement.....................................38
1. Introduction
This informational I-D has the objective of focusing the Internet
communications community on requirements for telephony devices using
SIP [3].
We base this information from developing and using a large number of
SIP telephony devices in carrier and private IP networks and on the
Internet. This deployment has shown the need for generic
requirements for SIP telephony devices and also the need for some
specifics that can be used in SIP interoperability testing.
SIP telephony devices, also referred to as SIP User Agents (UAs) can
be any type of IP networked computing device enabled for SIP based
IP telephony. SIP telephony devices can be SIP phones, adaptors for
analog phones and for fax machines, conference speakerphones,
software packages (soft clients) running on PCs, laptops, wireless
connected PDAs, 'Wi-Fi' SIP mobile phones, as well as other mobile
and cordless phones that support SIP signaling for real time
communications.
SIP devices MAY also support various other media besides voice, such
as text, video, games and also possibly other Internet applications;
however the non-voice requirements are not specified in this
document, except when providing enhanced telephony features, as will
be shown.
The objectives of the requirements are a minimum set of
interoperability and multi-vendor supported core features, so as to
enable similar ease of purchase, installation and operation as found
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for standard PCs, analog feature phones or mobile phones. Given the
cost of some feature rich display phones may approach the cost of
PCs and PDAs, and the larger number of phones compared to PCs,
similar or even better ease of use as compared to personal computers
and networked PDAs is expected by both end users and network
administrators.
As will be seen from the following, SIP telephony devices are highly
complex IP endpoints that speak many Internet protocols, have audio
and visual interfaces and require functionality targeted at several
constituencies: 1) End users, (2) service providers and network
administrators and (3), manufacturers, as well as system
integrators.
The high complexity of SIP telephony devices is a normal consequence
of placing Internet services in the endpoints.
2. Generic Requirements
We present here a minimal set of requirements that MUST be met by
all SIP telephony devices, except where SHOULD or MAY is specified.
2.1 Link Layer Requirements
SIP devices MUST support either:
Link-1: Wired Ethernet IEEE 802.3 10Base-T 10 Mb/s Half Duplex, or
Link-2: Wireless Ethernet 802.11a/b/g
SIP devices MAY also support other link layer protocols, such as
Link-3: IEEE 802.3 10Base-T Full Duplex
Link-4: IEEE 802.3 100Base-T Half Duplex
Link-5: IEEE 802.3u 10/100Mb Auto-sensing
Link-6: SIP devices MAY support VLAN tagging as per IEEE 802.1q
Link layers used in 3rd generation mobile phone networks are out of
the scope for this document.
Power over Ethernet
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Power-1: SIP telephony devices intended for desktop use MAY support
in-line power over Ethernet as specified in IEEE 802.3af.
Integrated Switch/Hub
SIP devices designed for wired Ethernet SHOULD have an uplink port
such that another IP device, such as a personal computer and MAY
share the network connection. SIP clients MUST prioritize the
transmission of the RTP traffic over the shared network connection.
2.2 IP Requirements
IP-1: SIP telephony devices MUST be able to acquire an IP address
by:
Automatic IP address configuration using DHCP, or
Manual IP address entry from the device.
IP-2: SIP devices MUST support multiple DNS entries. If the primary
DNS server does not respond to a DNS request, a secondary DNS server
MUST be queried.
IP-3: SIP devices MUST support the IPv4 DSCP field for RTP streams
that supercedes the TOS bits described in RFC 791. The DSCP bit
setting MUST be possible to be configured by either the user or
automatically by the downloaded configuration data. The Assured
Forwarding DSCP value Low Drop Precedence for RTP voice packets MUST
be 100010 [4].
IP-5: SIP devices SHOULD support IP version 6.
2.3 SIP Transport Requirements
Transport-1: SIP devices MUST support UDP transport of SIP messages.
Transport-2: SIP devices MUST support TCP transport of SIP messages.
Transport-3: SIP devices MAY support RSVP (RFC 2205).
2.4 SIP User Agent Services
The requirements listed in this section SHOULD be used for device
testing. To verify correct functionality for specific services, the
support for the requirements in the next section ôSupport for SIP
Servicesö SHOULD be tested.
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SIP telephony devices SHOULD support the guidelines for the
distributed model of multi-party call control for SIP [5].
The various call features listed here are also described in detail
in the SIP Service Examples [6].
SIP-1: SIP telephony devices MUST support RFC 3261 [3].
2.4.1 DNS Lookup and ENUM Support
SIP-2, DNS SRV: SIP devices MUST support RFC 3263 [7] for locating a
SIP Server and select a transport protocol using NAPTR. When making
a SRV query, the client MUST use the additional information in the
response that contains the IP addresses for the A records.
If the DNS additional information is not present, the client MUST
make DNS A record queries to resolve the host names.
If the destination SIP device is specified as an IP address, the SIP
client MUST not attempt to resolve the address with DNS as specified
in RFC 3263.
If the destination SIP device is a string value, the SIP client MUST
make normal DNS SRV and A record queries as specified in RFC 3263.
Clients SHOULD support ENUM lookup as specified in the update to RFC
2916 [8]
2.4.2 Basic Telephony
SIP-3, do not disturb: Users MUST be able to set the state of the
device to do not disturb (DND).
The change of the DND state SHOULD be communicated in a NOTIFY
message with a tuple for this device to a configured presence
server.
Re-invite: Clients MUST respond to new INVITES with a ô486 Busy
Hereö. Clients MUST respond to re-INVITES on existing dialogs as
normal behavior.
SIP-4, call hold resume: SIP clients MUST follow RFC 3264 [9] when
placing a call on hold. More specifically, the a=sendonly attribute
MUST be used. The SDP answer of SIP clients that are being placed on
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hold MUST NOT contain "held" SDP, unless the user session was
originally on hold.
SIP-5, multiple calls: SIP clients that support call on hold MUST be
able to support at least two or more calls. By placing the current
call ôon holdö, the client MUST be able to initiate or receive
another call.
SIP-6, call waiting indicator: SIP clients MUST support a call
waiting indicator. When already participating in a call, the user
MUST be alerted audibly and/or visually of another incoming call.
The user MUST be able to enable/disable call waiting.
SIP-7, message waiting indicator: SIP clients MUST support SIP
message waiting [10] and the integration with message store
platforms.
SIP-8, local dial plan: SIP clients MAY support a local dial plan.
The dial plan MUST consist of a pattern string to match dial digits,
and the ability to strip and/or append prefix digits, and/or append
suffix digits and send messages directly to another SIP device,
bypassing the proxy.
When using URL's and calling in the local domain, the local domain
(@domain) MAY be appended to facilitate calling.
SIP-9, transfer: SIP devices MUST support REFER and NOTIFY as
required to support transfer [11]. SIP clients MUST support escaped
headers in the Refer-To: header.
SIP-10, unattended transfer: SIP devices MUST support an unattended
transfer. SIP clients MUST support escaped headers in the Refer-To:
header.
SIP-11, attended call transfer: SIP devices MUST support attended
call transfer. SIP clients MUST support escaped headers in the
Refer-To: header.
SIP-12, device based conferencing: SIP devices MAY be able to
support device based conferencing. A SIP client MAY be able to
initiate and mix the audio streams of at least 2 separate calls
(i.e. 3 way conference calling).
SIP-13, DMTF in-band mixing: SIP devices MUST generate in-band DTMF
tones for use with the G.711 codec.
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SIP-14, DTMF RTP payload: SIP clients MUST be able to send DTMF
specified by RFC 2833 [12].
RFC 2833 negotiation must behave as follows: Receiving endpoint must
reply with the payload type sent by the initiator. For example, if
the initiating client sends payload type 101, the receiving endpoint
must reply with payload type 101.
Payload type negotiation MUST comply with RFC 3264 and with the
registered MIME types for RTP payload formats in RFC 3555.
The payload type MUST remain constant throughout the session. For
example, if an endpoint decides to renegotiate codecs or put the
call on hold, the payload type for the re-invite MUST be the same as
the initial payload type. SIP devices SHOULD support Flow
Identification (FID) as defined in RFC 3388 [13].
SIP-15, 180 ignores earlier media: SIP devices MUST generate local
ringing and MUST ignore any early RTP media when a ô180 Ringingö
response is received.
SIP-16, play single early media stream: SIP devices MUST play the
first RTP stream and ignore any other RTP media streams when a ô183
Session Progressö response is received.
SIP-17, use the last 18x message received: SIP devices MUST obey the
last 18x message received when multiple 18x responses are received.
If the last response is ô180 Ringingö; the client MUST generate
local ringing. If the last response is ô183 Session Progressö; the
client MUST play the RTP stream.
SIP-18, call-info: SIP devices with a display MUST support the call-
info header and depending on the display capabilities MAY for
example display an icon or the image of the caller.
SIP-19, error-info support: SIP devices MUST support the Error-Info
header.
SIP-20, reason phrase display: If the SIP device displays prior
response messages, the client MUST use the ôReason Phraseö of the
response.
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The client MAY use an internal ôStatus Codeö table if there was a
problem with the language negotiation.
SIP-21: SIP devices MUST support music on hold as shown in "SIP
Service Examples" [6].
SIP-22: SIP devices SHOULD support the OPTION method as per RFC
3261.
SIP-23, fax support: SIP adapter devices (for analog phone lines)
MUST support the ITU-T T.38 standard [14]. SIP devices MUST fallback
to G.711 if T.38 fails.
2.4.3 Multi-line Requirements
SIP-24, multi-line support: Multi-line SIP devices MUST register
using more than one set of credentials.
SIP-25, multi-line do not disturb: SIP multi-line devices MUST be
able to set the state of the client to do not disturb on a per line
basis. Clients MUST respond to new INVITES with a ô486 Busy Hereö.
Clients MUST respond to re-INVITES on existing dialogs as normal.
SIP-26, multi-line call waiting indicator: Multi-line SIP devices
MUST support multi-line call waiting indicators. When already
participating in a call, the user MUST be alerted audibly and/or
visually of another incoming call. This setting MUST be provisioned
by the user.
SIP devices with multiple identities (ie. registrations/lines) MUST
allow the call waiting indicator to be set on a per identity basis.
If the call waiting is set for an identity, the client MUST respond
with ô486 Busy Hereö when an incoming call to that identity is
received and the client has an existing call with any of the
identities.
SIP-27, multi-line ring tones: SIP devices MUST be able to provision
a different ring tone for each line (i.e. registration or static
identity).
2.4.4 User Mobility
SIP-28, dynamic login/logout for user mobility: SIP devices SHOULD
support user mobility. SIP clients MAY store a static profile in
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non-volatile memory so that this information is available during the
power up sequence. SIP clients MAY allow a user to walk up to a
client, login, and be able to send and receive calls with his/her
profile information.
2.4.5 Emergency Features
SIP-29, For emergency numbers (e.g. 911, SOS URL) the client MUST
send the credentials (username and password) of the static profile.
SIP-30, Priority header: SIP devices SHOULD support the Priority
header for such applications as emergency calls or for selective
call acceptance.
SIP-31: SIP telephony devices that are used in environments that
support emergency preparedness SHOULD also support the sending and
receiving of the Resource-Priority header as specified in [15]. The
resource priority header influences the behavior for message routing
in SIP proxies and PSTN telephony gateways and is different from the
SIP Priority header specified in RFC 3261. Users of SIP telephony
devices may want to be interrupted in their lower-priority
communications activities if such an emergency communications
request arrives.
2.4.6 Interactive text support
SIP telephony devices such as SIP display phones and IP-analog
adapters SHOULD support the accessibility for user requirements for
the deaf, hard of hearing and speech impaired individuals as
described in RFC 3351 [16] and also for interactive text [17]
communications.
Note: SIP telephony devices supporting Instant Messaging based on
the SIMPLE standard allow text conversation based on blocks of text.
However, interactive text conversation is often preferred here due
to its streaming-like nature.
SIP-32: SIP telephony devices SHOULD provide a way to input text and
to display text through any reasonable method. Built-in user
interfaces, standard wired or wireless interfaces, and/or support
for text through a web interface are all considered reasonable
mechanisms. In addition, SIP telephony devices SHOULD provide an
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external standard wired or wireless interface or interfaces to
connect external input (keyboard, mouse) and display devices.
SIP-33: SIP telephony devices which include a display, or have a
facility for connecting an external display, MUST include protocol
support as described in RFC 2793 for real-time interactive text.
There may be value of having RFC2793 support in a terminal also
without a visual display. A synthetic voice output for the text
conversation may be of value for all who can hear, and thereby
having the opportunity to have a text conversation with other users.
SIP-34: A SIP telephony device MAY provide analog adaptor
functionality through an RJ-11 FXO port to support FXS devices.
A 2.5 mm audio port MAY also be provided, especially for portable
SIP devices, such as PDAs and 'Wi-Fi' SIP mobile phones.
If an RJ-11 (FXO) port is provided, then it MAY support a gateway
function from all text-telephone protocols according to ITU-T
Recommendation V.18 to RFC 2793 text conversation (in fact this is
encouraged in the near term during the transition to widespread use
of SIP telephony devices). If this gateway function is not included
or fails, the device MUST pass-through all text-telephone protocols
according to ITU-T Recommendation V.18, November 2000, in a
transparent fashion.
2.5 Support for SIP Services
SIP devices used for enterprise communications SHOULD support the
call flows for the basic and enhanced SIP services. The list here
MAY be used for system integration testing to support specific
commercial services.
The schema for uploading the identity from a PDA is outside the
scope of these requirements.
The call flows illustrated in the references shown below assure not
only minimal support for SIP phones, as required for PSTN-style
consumer services, but also for the most widely used Centrex-style
and PBX-style services.
All services shown here are compliant with the multiparty party call
control framework for SIP [5].
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The following IETF references for rich presence, instant messaging,
caller preferences and service mobility specify SIP specific
services that go beyond the capability of PSTN and PBX based
services and can be best supported by SIP telephony devices.
Srv-1: SIP Call Flow Examples [18],
Srv-2: SIP Service Examples [19],
Srv-3: SIP PSTN call flows [20],
Srv-4: Third Party Call Control in SIP [21],
Srv-5: Other SIP call control and multiparty features [5],
Srv-6: SIP devices MAY support conferencing services [22] for voice
and IM [23], so as to be able act as host for a 3-way conference at
least.
Srv-7: Rich Presence based services [24],
Srv-8: Caller and called party preferences [25],
Srv-9: Service mobility: SIP desk devices MAY allow roaming users to
upload their identity so as to have access to their services and
preferences from the home SIP server. Examples of user data to be
available for roaming users are: User service ID, the dialing plan,
personal directory and caller/called party preferences.
2.6 SIP and Other Related Protocols
SDP: SIP devices MUST support Session Description Protocol, RFC 2327
[26].
RTP/RTCP: SIP devices MUST support Real-Time Protocol and Real-Time
Control Protocol, RFC 1889. SIP devices SHOULD use RTCP Extended
Reports for logging and reporting on network support for voice
quality [27] and MAY also support [28].
SIP clients MUST support the Simple Network Time Protocol (RFC2030),
or use the Date: header of the 200 OK in response to a REGISTER
request.
Network Management
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SNMP: SIP clients SHOULD support SNMP reporting. SIP clients SHOULD
support the RTP and RTCP MIBs to report jitter, delay, and packet
loss.
2.7 SIP Security
Sec-1: SIP devices MUST support digest authentication as per RFC
3261.
Sec-2: SIP devices MUST be able to password protect configuration
information and administrative functions.
Sec-3: SIP devices MUST not display the password to the user or
administrator after it has been entered.
Sec-4: SIP clients MUST be able to disable remote access, i.e. block
incoming SNMP, HTTP, and other services not necessary for basic
operation.
Sec-5: SIP clients MUST be able to reject an incoming INVITE where
the user-portion of the SIP request URI is blank or does not match a
provisioned Contact. The setting to accept/reject MUST be
provisioned.
Sec-6: SIP clients MUST be able to reject an incoming INVITE when
the message does not come from the proxy or proxies where the client
is registered. For DNS SRV specified proxy addresses, the client
must accept an INVITE from all of the resolved proxy IP addresses.
2.8 Voice Codecs
Internet telephony devices face the problem of supporting multiple
codecs due to various historic reasons, on how telecom industry
players have approached codec implementations and the serious
intellectual property and licensing problems associated with most
codec types.
Many, but not all voice codec payload types are described in RFC
3550 [29], while RFC 3555 lists 22 registered MIME subtypes for
audio codecs.
Codec-1: Three main classes of voice codecs MAY be supported by
Internet telephony devices; (1) default G.711, (2) compressed and
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(3) wideband. At least two codecs, the default G.711 codec and one
compressed codec listed below MUST be supported.
1. SIP telephony devices MUST support AVT payload type 0 (G.711
uLaw) as the default codec. The packet size MUST be 20 milliseconds.
The matching ITU-T Appendix I and Appendix II decoders SHOULD also
be supported.
2. The compressed Internet Low Bit Rate codec (iLBC) [30], [31] MUST
be supported.
Other compressed codecs SHOULD be supported. Compressed Voice codecs
used in 2nd and 3rd generation mobile phone systems, such as various
GSM codecs are also found in various implementations and SHOULD be
supported.
The narrow bandwidth codecs such as G.723.1 with such low speed as
5.3 kb/s and 6.3 kb/s (without RTP/UDP/IP overhead) as to work well
even on dial-up access MAY be supported.
Compressed codecs such as G.729 derived from delta-PCM encoding,
found in networks with frugal Internet access bandwidth using frame
relay or DSL access MAY be supported.
3. Wideband codecs using typically 16 kHz voice sampling for better-
than-PSTN voice quality, such as G.722 and other MAY be supported.
Such codecs are found in conferencing systems to increase the
perceived quality of conferencing.
Note: A summary count reveals up to 25 and more voice codec types
currently in use. The authors believe there is a need for a single
multi-rate Internet codec, such as [32] that can effectively be
substituted for most of the multiple codec types listed here, except
the Internet Low Bit Rate codec (iLBC) and avoid the complexity and
cost implementers and service providers alike are faced by
supporting so many codec types, including especially those that have
not been developed specifically for Internet use.
Codec-2, codec negotiation: Endpoints MUST follow these guidelines
in RFC 3264: Initiator specifies "preferred" codec and the receiver
has "final" choice of codec selected.
This includes the codec negotiations for the various G.723 and G.729
codec types listed in RFC 3555.
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Both endpoints MUST use the first matching codec listed by the
receiver.
If an endpoint cannot dynamically switch between available codecs,
it MUST offer a single codec and send a new INVITE with another
codec if the original fails due to the SIP 488 "Media Unsupported"
message.
Codec-3, comfort noise: SIP devices MAY support comfort noise
generated in the receiver, without using up end-to-end bandwidth. It
is also RECOMMENDED that SIP clients comply with performance
specified for the "handset receive comfort noise" requirements
outlined in the ANSI/EIA/TIA-810-A-2000 standard.
2.9 Voice-Telephony Requirements
Voice-1, loudness: SIP telephony devices MUST conform to the
electro- acoustical requirements for send loudness rating (SLR),
receive loudness rating (RLR), weighted terminal coupling loss
(TCLw), stability loss, etc.) of the TIA/EIA standards [33], and
[34].
Stability loss is a measure of the contribution of the telephone set
or terminal to the overall connection stability requirements.
Stability loss is defined as the minimum loss from the terminal
digital input (receive) to the terminal digital output (transmit),
at any test frequency.
Voice-2, stability loss: SIP device SHOULD meet the following
stability loss requirements.
The stability or minimum loss, per ITU-T G.177, TIA/EIA-810-A and
TIA/EIA-579-A, at any voice-band frequency SHOULD be greater than 6
dB, and preferably greater than 10 dB. Digital telephone sets or
terminal equipment with adjustable receive level SHOULD maintain
stability over the entire range of adjustable receive levels.
Voice-3, speakerphone: SIP devices MAY provide a full-duplex
speakerphone with echo and side-tone cancellation.
Voice-4, programmable ring-tones: SIP device MAY be able to use
different ring-tones based on the caller identity (i.e. From:
header).
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2.10 International Requirements
International-1, language support: SIP devices SHOULD indicate the
preferred language using SIP Caller Preferences. The setting for
this header MUST be provisioned.
International-2, international display support: SIP devices intended
to be used in various language settings, MUST support other
languages for menus, help, and labels.
2.11 Support for Applications
The following requirements apply to functions placed in the SIP
telephony device.
App-1, SIMPLE Integration: SIP devices that support presence MUST
provide a buddy list and use SIP extensions to leverage presence
[35].
App-2, address-book integration: SIP devices SHOULD allow a 3rd
party to initiate a call for the client, such as using the address
book in the PC to initiate a call.
App-3, LDAP phonebook: SIP devices MAY support LDAP for client-based
directory lookup.
App-4, automatic ring-down: SIP devices MAY support a phone setup
where a URL is automatically dialed when the client goes off-hook.
App-5, hold ring-back: SIP devices MAY ring after a call has been on
hold for a predetermined period of time, typically 3 minutes. This
time value MUST be provisioned.
2.12 Web-based Feature Management
Web-1: SIP devices SHOULD support an internal web server to allow
users to manually configure the phone and to set up personal phone
services such as the address book, speed-dial, ringer tones, and
last but not least the call handling options for the various lines,
aliases, in a user friendly fashion. Web pages to manage the SIP
telephony device SHOULD be supported by the individual device, or in
managed networks from centralized web servers. Managing SIP
telephony devices SHOULD NOT require special client software on the
PC or on a management console.
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Web-2: The telephone settings MAY be accessible to authenticated
users or operations personnel from remote locations.
2.13 Firmware Update
Firm-1: SIP devices MUST be able to upgrade their firmware as
described in section 3.
2.14 Firewall/NAT Traversal
The following requirements allow SIP clients to properly function
behind various firewall architectures.
FW/NAT-1, outbound proxy support: SIP devices MUST support a default
domain used for NAT traversal. SIP devices MUST have the capability
to be configured so that the default domain and the outbound SIP
proxy are different.
The provisioned user identity on the device MUST include a full URL
to be included in the SIP From: header or a provisioned domain name
MUST be appended.
Configuration Information
Name: userA
Proxy Address: sip.outbound.domain.com
Domain: domain.com
Example Message sent to sip.outbound.domain.com
REGISTER sip:domain.com SIP/2.0
To: sip:userA@domain.com
From: sip:userA@domain.com
Contact: sip:10.10.10.215
FW/NAT-2, NAT capable configuration: SIP devices MUST be able to
operate behind a static NAT/PAT (Network Address Translation/Port
Address Translation) device using the STUN protocol [36]. SIP
clients MUST be able to populate SIP messages with the public,
external address of the NAT/PAT device and use specific port ranges
for RTP.
FW/NAT-3, UPnP capable configuration: SIP devices MAY be able to
operate with a UPnP (http://www.upnp.org/) firewall device. UPnP
will support the traversal of the local NAT/FW and is adequate on
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its own when no other NATs are placed in the service provider
network.
FW/NAT-4, STUN capable configuration: SIP telephony devices MUST be
able to operate with a STUN server.
2.15 Device Interfaces
SIP telephony devices MAY have various types of interfaces, such as
resembling a desktop phone, cordless phone, mobile phone, handheld
computer, laptop computer and MAY have various interface models,
such as for phones, IM GUI or personal organizer. Given the variety
of possible interfaces, the generic requirements only can be listed
here.
Int-1: SIP telephony devices MUST have a telephony-like dial-pad and
MAY have telephony style buttons like mute, redial, transfer,
conference, hold, etc.
Int-2: SIP telephony devices MUST have a convenient way for entering
SIP URLs and phone numbers. This includes all alphanumeric
characters allowed in legal SIP URLs. Possible approaches include
using a web page, display and keyboard entry or graffiti for PDAs.
Phone number entry SHOULD be supported in human friendly fashion, by
allowing the usual separators and brackets between digits and digit
groups.
Int-3: SIP telephony devices MUST have two types of interface
capabilities, for both phone numbers and URLs, both accessible to
the end user.
1. SIP device configuration and management interface:
SIP telephony adapters and high end phones MAY support SNMP v.3 for
managing the device. The required MIB is outside the scope of this
memo.
The access to the SIP device configuration interface MAY be blocked
by the service provider so as not allow misconfiguration of the
settings.
2. End user options interface: Such as personal address book, auto-
forwarding, ringer tones, etc.
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Desktop and other phone-style SIP devices can meet the above
requirements with a device web page. Device web pages may also
facilitate remote device settings from a help desk, without user
intervention.
3. Automatic Configuration
Automatic SIP telephony device configuration SHOULD use the
processes and requirements described in [37] and [38].
The user name or the realm in the domain name SHOULD be used by the
configuration server to automatically configure the device for
individual or group specific settings, without any settings by the
user.
Image and service data upgrades SHOULD also not require any settings
by the user.
4. Configuration Settings
Besides network parameters, SIP telephony devices MAY also be
configured with user data described here.
Settings are the information on a client that it needs to be a
functional SIP endpoint. It is an implementation choice whether the
device stores the data across power cycles and hardware restarts or
it reloads the data every time upon startup. The settings defined in
this document are not intended to be all inclusive. It MUST be
possible for vendor specific parameters to be added. Parameters
which are not understood by an end point MUST be ignored.
The list of available configuration settings includes settings that
MUST, SHOULD or MAY be used by all devices (when present) and that
make up the common denominator that is used and understood by all
devices. However, the list is open to vendor specific extensions
that support additional settings, which enable a rich and valuable
set of features.
Settings MAY be read-only on the device. This avoids the
misconfiguration of important settings by inexperienced users
generating service cost for operators. This draft describes how
operator MAY protect some settings from end users.
In order to achieve wide adoption of any configuration settings
format it is important that it not be excessive in size so as to
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allow modest devices to use it. Any format SHOULD be structured
enough to allow flexible extensions to it by vendors.
Settings may belong to the device or to a line. When the endpoint
acts in the context of a line, it will first try to look up a
setting in the line context. If the setting can not be found in that
context, the device will try to find the setting in the device
context. If that also fails, the device MAY use a default value for
the setting.
The line concept allows configuration of phones in a user specific
context. It simplifies unconstrained seating in offices, can support
roaming users and allows users to subscribe to more than one service
provider.
In principle, all settings MAY be present in line and in device
context. For some settings (e.g. the MAC address of the device),
devices MAY set restrictions on the availability of settings in
either line or device context.
4.1 Device ID
A device setting MAY include some unique identifier for the device
it represents. This MAY be an arbitrary device name chosen by the
user, the MAC address, some manufacturer serial number or some other
unique piece of data.
4.2 Network Related Settings
Network-1: SIP Ports. The port that MUST be used for a specific
transport protocol MAY be indicated with the SIP ports setting. If
this setting is omitted, the device MAY choose any port.
Network-2: Quality of Service. The Quality of Service settings for
outbound packets SHOULD be configurable for network packets
associated with call signaling (SIP) and media transport (RTP/RTCP).
These settings help network operators identifying voice packets in
their network and allow them to transport them with the necessary
quality. The settings are independently configurable for the
different transport layers and signaling, media or administration.
For both categories of network traffic, the device SHOULD permit
configuration of the type of service settings for both layer 3 (IP
DiffServ) and layer 2 (IEEE 802.1D/Q) of the network protocol stack.
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Network-3: Network parameters. The parameters for SIP (like timer
T1) and other network related settings MAY be indicated. An example
of usage would be the reduction of the DNS SRV failover time.
Network-4: RTP Port range. A range of port numbers MUST be used by a
device for the consecutive pairs of ports which MUST be used to
receive audio and control information (RTP and RCTP) for each
concurrent connection. This is required to support firewall
traversal. This again helps network operators to identify voice
packets and makes it possible to configure port ranges on firewalls
only for voice packets.
Network-5: Registration period. A line definition MAY contain a
period (in seconds) which once exceeded will cause the device to re-
register its registration server(s). The default value is one hour.
Network-6: Default Call Handling. All of the call handling settings
defined below in section 5.3.2 can be defined here as default
behaviors.
Network-7: Outbound Proxy. The outbound proxy for a line or for a
device MUST be set. The address is encoded as SIP URI. The setting
MAY contain alternative outbound proxies, which MAY be used in case
of a server failure.
Using this setting, private networks can control outbound traffic
and send it through an application layer gateway.
Network-8: Default Outbound Line. The default outbound line SHOULD
be a global setting (not related to a specific line). This setting
MUST not be used as part of a line definition.
Network-9: SIP Session Timer. The re-invite timer allows user agents
to detect broken sessions caused by network failures. A value
indicating the number of seconds for the next re-invite SHOULD be
used if provided. If there is no value provided, the device MAY use
a default value (e.g. 3600 seconds).
4.3 Address Completion
As most telephone users are used to dialing digits to indicate the
address of the destination, there is a need for specifying the rule
by which digits are transformed into a URL (usually SIP URL or TEL
URL).
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Dial-1: SIP phones need to understand entries into the phone book of
the most common separators used between dialed digits, such as
spaces, angle and round brackets, dash and dots.
Dial-2: Dial Plan and/or Dial/OK key. A dial plan which defines the
maximum expected length of a typical telephone number MAY be used.
If no dial plan is used, the device MUST have a "Dial" or "OK" key,
similar to mobile phones.
Zero or more digit maps which map a dial plan and a SIP address to
which phone numbers of that type SHOULD be routed to SHOULD be
supported. The digit maps define numeric patterns that when matched
define:
1) A rule by which the end point can judge that the user has
completed dialing, and
2) A rule to construct a URL from the dialed digits, and optionally
3) An outbound proxy to be used in routing the SIP INVITE.
A critical timer MAY be provided which determines how long the
device SHOULD wait before dialing if a dial plan contains a T
character. It MAY also provide a timer for the maximum elapsed time
which SHOULD pass before dialing if the digits entered by the user
match no dial plan.
Dial-3: Default Digit Map. The end point SHOULD support the
configuration of a default digit map. If the end point does not
support digit maps, it SHOULD at least support a default digit map
rule to construct a URL from digits. If the end point does support
digit maps, this rule applies if none of the digit maps match.
Dial-4: Overlap-Dial. Some operators support overlap dialing and
MAY want to indicate to the SIP devices that this mode is to be
used. This setting is Boolean and MAY be set to true or false.
4.4 Audio
Audio-1: Codecs. In some cases operators want to control which
codecs MAY be used in their network. The desired subset of codecs
supported by the device MUST be configurable along with the order of
preference. Service providers MUST have the possibility of plugging
in their own codecs of choice.
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The range for parameters of the codecs MUST be adjustable. This
includes the packet length (ms of audio), which is a function of
the sample rate.
However, the negotiation of the media for individual calls is being
done on a per call basis.
Audio-2: DTMF method. DTMF allows different ways of indicating that
a key has been pressed as per RFC 2833. The method for sending these
events SHOULD be configurable with the order of precedence.
Audio-3: Silence suppression. It SHOULD be possible to disable
silence suppression on the end point such that RTP audio packets are
sent even if silence is detected.
4.5 Local and Regional Parameters
Certain settings are dependent upon the devices regional location,
such as the daylight saving time rules and the time zone.
Regional-1: Time Zone. A time zone MAY be specified for the user.
Where one is specified; it SHOULD use the scheme used by the Olson
Time One database [39]. Examples of the database naming scheme are
Asia/Dubai or America/Los Angeles where the first part of the name
is the continent or ocean and the second part is normally the
largest city on that time-zone.
Regional-2: UTC Offset. An offset from Coordinated Universal Time
(UTC) in seconds MAY be used.
Different rules exist for when daylight saving time (DST) starts and
ends. For example in North America begins on the first Sunday in
April whereas in Western Europe is begins on the last Sunday in
March.
Regional-3: A DST rule MAY be used by the device.
The network addresses of SNTP (RFC 2030) time servers where the
device can get a centrally defined time value MAY be used.
Regional-4: The time server MAY be used. DHCP is the preferred way
to provide this setting. Setting the correct language is important
for simple installation around the globe.
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Language-1: Language settings MAY be deployed. A language MAY be
specified for a device. Where it is specified it SHOULD use the
codes defined in RFC3066 [40] to provide some predictability.
Language-2: It is RECOMMENDED that servers set the Language as
writable, so that the user MAY change this. This setting SHOULD NOT
be line related.
Language-3: A SIP UA MUST be able to parse and accept requests
containing international characters encoded as UTF-8 even if it
canÆt display those characters in the user interface.
4.6 Inbound authentication
SIP allows a device to limit incoming signaling to those made by a
predefined set of authorized users from a list and/or with valid
passwords.
In-Auth-1: A device SHOULD support the setting as to whether
authentication (on the device) is required and what type of
authentication is REQUIRED: NONE or DIGEST.
In-Auth-2: If inbound authentication is enabled then a list of
allowed users and credentials to call this device MAY be used by the
device. The credentials MAY contain the same data as the credentials
for a line (i.e. URL, user, password digest and realm). This applies
to SIP control signaling as well as call initiation. The list shows
for example who is allowed to send a REFER or an INVITE with the
Join or Replaces header.
4.7 Voice message settings
VM-1: Various voice message settings require the use of URL's as
specified in [41].
VM-2: The message waiting indicator (MWI) address setting controls
where the client SHOULD SUBSCRIBE to a voice message server and what
MWI summaries MAY be displayed [42].
4.8 Phonebook and Call History
IP Telephony devices MAY store locally a phonebook and also the
history of recent calls.
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Phonebook-1: SIP telephony devices MAY store telephone book entries
locally and/or MAY use a central LDAP directory.
Call History-1: SIP telephony devices MAY store locally a recent
(limited) call history. Devices that are not able to differentiate
call history entries between "tried" and "dialed" SHOULD use
"dialed".
4.9 User Related Settings and Roaming
A device MAY specify the user which is currently registered on the
device. This SHOULD be an address-of-record URL specified in a line
definition.
The purpose of specifying which user is currently assigned to this
device is to provide the device with the identity of the user whose
settings are defined in the user section. This is primarily
interesting with regards to user roaming. Devices MAY allow users to
sign-on to them and then request that their particular settings be
retrieved. Likewise a user MAY stop using a device and want to
disable their lines while not present. For the device to understand
what to do it MUST have some way of identifying users and knowing
which user is currently using it. By separating the user and device
properties it becomes clear what the user wishes to enable or to
disable.
Providing an identifier in the configuration for the user gives an
explicit handle for the user. For this to work the device MUST have
some way of identifying users and knowing which user is currently
assigned to it.
One possible scenario for roaming is an agent who has definitions
for several lines (e.g. one or more personal lines and one for each
executive for whom the administrator takes calls) that they are
registered for. If the agent goes to the copy room they would sign-
on to a device in that room and their user settings including their
lines would roam with them. The alternative to this is to require
the agent to individually configure all of the lines individually
(this would be particularly irksome using standard telephone button
entry).
The management of user profiles, aggregation of user or device lines
and profile information from multiple management sources are
configuration server concerns which are out of the scope of this
document. However the ability to uniquely identify the device and
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user within the configuration data enables easier server based as
well as local (i.e. on the device) configuration management of the
configuration data.
UserID: User ID MAY be specified. If the user ID is specified, the
address-of-record URL MAY be specified for the line definition.
4.10 Line Related Settings
SIP telephony devices MUST use the line related settings, as
specified here.
4.11 Line Identification
A line represents an address-of-record identified by a URL.
There are many properties which MAY be associated with or SHOULD be
applied to the line or signaling addressed to or from the line.
Lines MAY be defined for a device or a user of the device. At least
one line MUST be defined in the configuration settings, this MAY
pertain to either the device itself or the user.
A line MUST provide an address or record URL which both
distinguishes the line and provides the URL which optionally will be
registered for the line.
It MUST be possible to specify at least one set of realm, user name
and authentication credentials for each line. The user name and
authentication credentials are used upon authentication challenges.
4.12 Maximum connections
A setting defining the maximum number of simultaneous connections
that a device can support MUST be used by the device. Obviously the
end point has some maximum limit, most likely determined by the
media handling capability. The number of simultaneous connections
may be also limited by the access bandwidth, such as of DSL, cable
and wireless users.
MaxConn: A SIP telephony device MAY support at least two
connections for three-way conference calls that are locally hosted.
5. Examples of Configuration Data
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The section describes the requirements and format for an
implementation of the settings described in section 4.
5.1. Requirements for Configuration Data Representation
From reading the preceding section 4, it is apparent that many of
the settings are composite and related. As the number and complexity
of the settings grows it is useful from an administration point of
view to be able to easily relate settings.
This document recognizes that as features multiply on devices, so
will the amount of settings. Any format proposed SHOULD be readily
and intuitively extensible.
5.2 Configuration Data Format
The choices for the configuration data formats are best left to the
discretion of the implementers and service providers.
Open Issue: The authors believe it would be useful to specify a
grammar for the default name space.
This document illustrates however using XML as the file format for
the configuration settings primarily for the reasons stated above.
XML naturally maps the settings defined in section 4.
Note for potential grammar designers and implementers: The authors
believe it is very useful to have CDATA sections in XML documents
where the content itself may break XML syntax rules. This is the
case of SIP URLs. An example of is given in Example E below.
XML namespaces are a useful tool when processing documents which MAY
contain elements from more than one source. The default namespace
for any XML document using the definitions described in this
document MUST define the default namespace in the root node with a
URL.
Vendors MAY add their own content within the XML document but MUST
provide qualified names with their own namespace.
The general format for the XML data is to have device and user
elements as direct children of the root node. Those elements will
contain all of the appropriate settings describe in section 3.
An example of an extension to the time zone setting is show below.
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<settings xmlnshttp://someurl
xmlns:acme=http://amce.com>
<device>
<id>00:d0:1e:00:1a:0e</id>
<locale>
<dstrule>NORTH AMERICA</dstrule>
<timezone>America/Los_Angeles</timezone>
<!-- vendor extension -->
<acme:timezonedisplay>"PST"</acme:timezonedisplay>
<timeserver>10.1.1.1</timeserver>
<language>US:English</language>
</locale>
</device>
<user/>
</settings>
5.3 Format Definition
The definitions of the elements and attributes will not be included
in this version of the draft, given that only examples are shown
here. The examples follow to only illustrate some concepts of the
format. Section 4 defines the requirements from which the XML
elements and attributes will be derived. The authors believe the
data format definitions and grammar for SIP telephony device
configuration data SHOULD be the object of separate documents.
5.4 Handling of Unrecognized Element Names
The default rule is that any element with an unrecognized name is
ignored (i.e. having an unrecognized namespace URI, or an
unrecognized local name within that namespace). This includes all of
the element content, even if it appears to use recognized names.
5.5 XML Configuration Data
This section aims to provide some samples of the settings defined in
section 4, using XML [43]. A complete grammar/schema definition is
not provided here, since this serves as an example only.
5.6 Device settings
A. Network Settings
<network>
<tcp>
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<port>5060</port>
</tcp>
<udp>
<port>5060</port>
</udp>
<rtp>
<ports>100</ports>
</rtp>
<dhcpLease>300</dhcpLease>
<externalIpAddress>10.1.1.1</externalIpAddress>
<httpOutboundProxy>
<ipAddress>10.1.1.1</ipAddress>
<port>80</port>
</httpOutboundProxy>
<ethnetDuplex value="full"/>
</network>
B. Address Completion
<addressCompletion>
<dialplan length="10"/>
<digitmap>
<pattern>91XXXXXXXX</pattern>
<targetAddress>sip:{digits}@provider1</targetAddress>
<outboundProxy>proxy.provider1:port</outboundProxy>
</digitmap>
<digitmap>
<pattern>011X*</pattern>
<targetAddress>sip:internation</targetAddress>
</digitmap>
</addressCompletion>
C. Audio
<audio>
<codecs>
<codec priority="1">G711</codec>
<codec priority="2">iLBC</codec>
<codec priority="3">G722</codec>
</codecs>
</audio>
D. Line default settings
<lineDefaults>
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<outboundProxy>10.1.1.1</outboundProxy>
<callHandling>
<busy behavior=busy/>
<callWaiting behavior=busy/>
</callHandling>
</lineDefaults>
E. Line definition for device
<line aor-url=<Extension 123>sip:1234@Pingtel.com
register=provision>
<credential>
<realm>Pingtel.com</realm>
<userId>anon</userId>
<passToken>password</passToken>
<credential>
<callHandling>
<maxConnections>2</maxConnections>
<available behavior=forward-no-answer>
<seconds>32<seconds>
<url>sip:admin@acme.com</url>
</available>
</callHandling>
</line>
In this example the outbound proxy and call handling settings
defined in the line default settings example SHOULD be used in
addition to the line definition.
Note: The authors' preference for potentially long values in XML is
to use an element rather than an attribute. Added to which, in an
element you can wrap values which would normally break the XML
syntax in a CDATA. This would allow SIP URLs to be formatted
without having to escape them.
Example:
<line register=öprovisionö>
<aor-url><[!CDATA[ôExtension 123ö<sip:1234@Pingtel.com>]]</aor-url>
5.7 User settings
F. Voice mail settings
<voicemail>
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<mwi>10.1.1.1</mwi>
<retrieve>10.1.1.2</retrieve>
</voicemail>
G. Line definition for user
<user>
<id><Fred Bloggs>sip:fbloggs@Pingtel.com</id>
<line aor-url=<Fred Bloggs>sip:fbloggs@Pingtel.com
register=register>
<credential>
<realm>Pingtel.com</realm>
<userId>fredb</userId>
<passToken>abdc342RRe</passYoken>
<credential>
<credential>
<realm>provider1.com</realm>
<userId>fredbloggs</userId>
<passToken>bdc42jjRe</passToken>
<credential>
<callHandling>
<available behavior=busy/>
</callHandling>
</line>
</user>
Credentials are supplied for two realms in this example. In this
example the outbound proxy and call handling settings defined in the
line default settings example SHOULD be used in addition to the line
definition.
6. IANA Considerations
SIP Event Package Registration for Configuration
Package name: SIP Telephony Device Configuration
Type: package
Contact: [Christian Stredicke]
Published Specification: This document.
MIME Registration for Application
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The MIME Registration for application/sip-endpoint-configuration is:
MIME media type name: application
MIME subtype name: sip-endpoint-configuration
Required parameters: none.
Optional parameters: none.
Encoding considerations: See SIP [3] message header definition.
Security considerations: See the "Security Considerations" in
Section 8 n this document.
Interoperability considerations: none
Published specification: This document.
Applications which use this media: SIP configuration server and
clients subscribing to these servers.
Additional information:
1. Magic number(s): N/A
2. File extension(s): N/A
3. Macintosh file type code: N/A.
7. Configuration Security
Please see also the above section 2.7 on SIP Security.
The device configuration MAY contain sensitive information that MUST
be protected. Examples include authentication information, private
address books and call history entries. Because of this, it is
RECOMMENDED to use an encrypted transport mechanism for
configuration data. Where devices use HTTP this could be TLS [44].
For devices which use FTP or TFTP for content delivery this can be
achieved using symmetric key encryption.
Access to retrieving configuration information is also an important
issue. A configuration server SHOULD challenge a subscriber before
sending configuration information.
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8. Changes
8.1 Changes since draft-sinnreich-sipdev-req-01
. Re-edited the section on Interactive text support for hearing
or speech disabled users.
. Shortened the sections on phonebook, call history and line
related settings.
. Deleted the section on ringer behavior.
. Updated and added references.
9. Acknowledgements
We would like to thank Rohan Mahy for contributing several
clarifications to this document and especially for the leadership
provided in the discussions on support for the hearing disabled.
These discussions have been concluded during the BOF on SIP Devices
held during the 57th IETF with help from Rohan Mahy and the
conclusions are reflected in the section on Interactive text support
for hearing or speech disabled users.
Arnoud van Wijk and Guido Gybels have been instrumental in driving the
specification for support of the hearing disabled.
The authors would also like to thank numerous persons for
contributions and comments to this Internet Draft: Henning
Schulzrinne, J÷rgen Bj÷rkner, Jay Batson, Eric Tremblay, Gunnar
Hellstr÷m, David Oran and Denise Caballero McCann, Brian Rosen, Jean
Brierre, Kai Miao, Adrian Lewis and Franz Edler. Jonathan Knight has
contributed significantly to earlier versions of parts of this
Internet Draft. Peter Baker has also provided valuable pointers to
TIA/EIA IS 811 requirements to IP phones that are referenced here.
10. Authors Addresses
Ian Butcher
Liquid Machines
10 Maguire Road
Lexington, MA 02421, USA
Phone: +1 782 861 1497
Email: ian1972@earthlink.net
Steven Lass
MCI
400 International Parkway
Richardson, TX 75081, USA
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EMail: steven.lass@mci.com
Phone: +1 972 729 4469
Daniel G. Petrie
Pingtel Corp.
400 W. Cummings Park
Suite 2200
Woburn, MA 01801, USA
Phone: +1 781 938 5306
Email: dpetrie@pingtel.com
Henry Sinnreich
MCI
400 International Parkway
Richardson, TX 75081, USA
EMail: henry.sinnreich@mci.com
Christian Stredicke
snom technology AG
Pascalstrasse 10e
10587 Berlin, Germany
Phone: +49(30)39833-0
Email: cs@snom.de
11. References
The references include both normative documents at the RFC level, as
well as informational references in the form of Internet Drafts as
they were available at the time of publishing this memo.
[1] RFC2026: "The Internet Standards Process -- Revision 3" by Scott
Bradner, IETF, October 1996.
[2] RFC 2119: "Key words for use in RFCs to Indicate Requirement
Levels" by Scott Bradner, IETF, 1997.
[3] J. Rosenberg et. al.: "SIP: Session Initiation Protocol, RFC
3261, IETF, June 2002.
[4] RFC 2597: "Assured Forwarding PHB Group" by Heinanen, J. et al.
IETF, June 1999.
[5] Mahy, R.et al., "A Call Control and Multi-party usage framework
for the Session Initiation Protocol (SIP)", work in progress,
IETF, March 2003.
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[6] Johnston, A. et al.: "SIP Service Examples", work in progress,
February 2003.
[7] RFC 3263: "Session Initiation Protocol (SIP): Locating SIP
Servers" by J. Rosenberg and H. Schulzrinne. IETF, June 2002.
[8] RFC 2916 bis: "The E.164 to URI DDDS Application (ENUM)" by
Falstom, P. and Mealling M. IETF, May 2003.
[9] RFC 3264: "An Offer/Answer Model with Session Description
Protocol (SDP)" by J. Rosenberg and H. Schulzrinne. IETF, June
2002.
[10] Mahy, R.: "A Message Summary and Message Waiting Indication
Event Package for SIP". Work in progress, IETF March 2003.
[11] RFC 3515: "The SIP Refer Method" by R. Sparks, IETF, April
2003.
[12] RFC 2833: "RTP Payload for DTMF Digits, Telephony Tones and
Telephony Signals" by H. Schulzrinne and S. Petrack. IETF, May
2000.
[13] RFC 3388: "Grouping of Media Lines in the Session Description
Protocol (SDP)" by G. Camarillo et al. IETF, December 2002.
[14] ITU-T Recommendation T.38.
[15] Johnston, A. et al.: "Session Initiation Protocol Torture Test
Messages". Work in progress, IETF, August, 2002.
[16] Schulzrinne, H. and Polk, J.: Communications Resource Priority
for SIP. IETF, March 2003. Work in progress.
[17] RFC 3351: User Requirements for the Session Initiation Protocol
(SIP) in Support of Deaf, Hard of Hearing and Speech-impaired
Individuals by Charlton, et. al. IETF, August 2002.
[18] Hellstr÷m, G. and Roy, R.R.: "Framework of requirements for
real-time text conversation using SIP". IETF, October 2003.
[19] Johnston, A. et al.: "Session Initiation Protocol Basic Call
Flow Examples". Work in progress, IETF, August 2003.
H. Sinnreich Informational [Page 35]
SIP Telephony Device Requirements February 2004
[20] Johnston, A. et al.: "Session Initiation Protocol Service
Examples", work in progress, IETF, February 2003.
[21] Johnston, A. and Donovan S: "Session Initiation Protocol PSTN
Call Flows". Work in progress, IETF, November 2003.
[22] Rosenberg, J., et al., "Best Current Practices for Third Party
Call Control in the Session Initiation Protocol", work in
progress, March 2003
[23] Johnston A. and Levin O.: "Session Initiation Protocol Call
Control - Conferencing for User Agents", work in progress,
IETF, April 2003.
[24] Rosenberg, J. and Isomaki A.: "Requirements for Manipulation of
Data Elements in Session Initiation Protocol (SIP) for Instant
Messaging and Presence Leveraging Extensions(SIMPLE) Systems",
work in progress, IETF, August 2003.
[25] Rosenberg, J., et al., "Rich Presence Information Data Format
for Presence Based on the Session Initiation Protocol (SIP)",
work in progress, IETF, August 2003.
[26] Rosenberg, J. et al.: "Caller Preferences and Callee
Capabilities for the Session Initiation Protocol (SIP)", work
in progress, IETF, September 2003.
[27] RFC 2327: "SDP: Session Description Protocol" by M. Handley and
V. Jacobson. IETF, April 1998.
[28] T. Friedman et al: "RTP Control Protocol Extended Reports (RTCP
XR)", work in progress, IETF, April 2003.
[29] Johnston, A. at al: "RTCP Summary Report Delivery to SIP Third
Parties", IETF, June 2003. Work in progress.
[30] H. Schulzrinne et al.: "RTP Profile for Audio and Video
Conferences with Minimal Control", RFC 1890, IETF, January
1996.
[31] Andersen,S.V. et al.: "Internet Low Bit Rate Codec", work in
progress, IETF March 2003.
[32] Duric A. et al.: "RTP Payload Format for iLBC Speech", work in
progress. IETF March 2003.
H. Sinnreich Informational [Page 36]
SIP Telephony Device Requirements February 2004
[33] Herlein, G: "RTP Payload Format for the Speex Codec", work in
progress, IETF, February 2003.
[34] TIA/EIA-810-A, "Transmission Requirements for Narrowband Voice
over IP and Voice over PCM Digital Wireline Telephones", July
2000.
[35] TIA-EIA-IS-811, "Terminal Equipment - Performance and
Interoperability Requirements for Voice-over-IP (VoIP) Feature
Telephones", July 2000.
[36] Rosenberg, J.: "A Presence Event Package for the Session
Initiation Protocol (SIP)", work in progress, IETF, January
2003.
[37] Rosenberg, J. et al: "STUN - Simple Traversal of User Datagram
Protocol (UDP) Through Network Address Translators (NATs)".
IETF, March 2003.
[38] Petrie, D.: "A Framework for SIP User Agent Configuration",
work in progress. IETF, February 2003.
[39] Petrie, D. and Jennings, C.: "Requirements for SIP User Agent
Profile Delivery Framework", work in progress, IETF, February
2003.
[40] P. Eggert, "Sources for time zone and daylight saving time
data." Available at http://www.twinsun.com/tz/tz-link.htm
[41] H. Alvestrand "Tags for the Identification of Languages", RFC
3066, IETF, January 2001.
[42] R. Mahy et al.: " A Multi-party Application Framework for SIP",
Internet Draft, IETF, June 2002, work in progress.
[43] Mahy, R.: "A Message Summary and Message Waiting Indication
Event Package for SIP", work in progress, IETF, march 2003.
[44] T. Bray, J. Paoli, C. Sperberg-McQueen and E. Maler,
"Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
Recommendation, October 2000, http://www.w3.org/TR/2000/REC-
xml-20001006.
[45] RFC 2818: "HTTP over TLS" by E. Rescorla. IETF, May 2000.
H. Sinnreich Informational [Page 37]
SIP Telephony Device Requirements February 2004
11. Full Copyright Statement
Copyright (c) The Internet Society (2001). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
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English.
The limited permissions granted above are perpetual and will not be
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This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
H. Sinnreich Informational [Page 38]
