Network Working Group B. Campbell
Internet-Draft J. Rosenberg
Expires: October 16, 2002 D. Willis
R. Sparks
dynamicsoft
H. Schulzrinne
J. Lennox
Columbia University
C. Huitema
B. Aboba
D. Gurle
Microsoft Corporation
D. Oran
Cisco Systems
April 17, 2002
Session Initiation Protocol Extension for Instant Messaging
draft-ietf-sip-message-03
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
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The list of current Internet-Drafts can be accessed at http://
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The list of Internet-Draft Shadow Directories can be accessed at
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This Internet-Draft will expire on October 16, 2002.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
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Instant Messageing (IM) refers to the transfer of messages between
users in near real-time. These messages are usually, but not
required to be, short. IMs are often used in a conversational mode,
that is, the transfer of messages back and forth is fast enough for
participants to maintain an interactive conversation.
The MESSAGE method is an extension to the Session Initation Protocol
(SIP) that allows the transfer of Instant Messages. MESSAGE requests
carry the content in the form of MIME body parts. MESSAGE requests
do not themselves initiate a SIP dialog; under normal usage each
Instant Message stands alone, much like pager messages. MESSAGE
requests may be sent in the context of a dialog initiated by some
other SIP request.
Since the MESSAGE request is an extension to SIP it inherits all the
request routing and security features of that protocol.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Overview of Operation . . . . . . . . . . . . . . . . . . . 4
3. UAC Processing . . . . . . . . . . . . . . . . . . . . . . . 5
4. Use of Instant Message URIs . . . . . . . . . . . . . . . . 6
5. Proxy Processing . . . . . . . . . . . . . . . . . . . . . . 6
6. UAS Processing . . . . . . . . . . . . . . . . . . . . . . . 6
7. Caller Preferences . . . . . . . . . . . . . . . . . . . . . 7
8. Congestion Control . . . . . . . . . . . . . . . . . . . . . 7
9. Method Definition . . . . . . . . . . . . . . . . . . . . . 8
10. Example Messages . . . . . . . . . . . . . . . . . . . . . . 10
11. Security Considerations . . . . . . . . . . . . . . . . . . 11
11.1 Outbound authentication . . . . . . . . . . . . . . . . . . 12
11.2 SIPS URIs . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.3 End-to-End Protection . . . . . . . . . . . . . . . . . . . 12
11.4 Replay Prevention . . . . . . . . . . . . . . . . . . . . . 12
11.5 Using message/cpim bodies . . . . . . . . . . . . . . . . . 13
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 13
13. Changes to This Document . . . . . . . . . . . . . . . . . . 13
13.1 Changes introduced in draft-ietf-sip-message-03 . . . . . . 13
13.2 Changes introduced in draft-ietf-sip-message-02 . . . . . . 13
13.3 Changes introduced in draft-ietf-sip-message-01 . . . . . . 14
13.4 Changed Introduced in draft-ietf-sip-message-00 . . . . . . 14
13.5 Changes Introduced in draft-ietf-simple-im-01 . . . . . . . 15
13.6 Changes Introduced in draft-ietf-simple-im-00 . . . . . . . 15
13.7 Changes Introduced in draft-rosenberg-impp-im-01 . . . . . . 15
14. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 15
Normative References . . . . . . . . . . . . . . . . . . . . 16
Informational References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 17
Full Copyright Statement . . . . . . . . . . . . . . . . . . 19
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1. Introduction
Instant messaging is defined as the exchange of content between a set
of participants in near real time. Generally, the content is short
text messages, although that need not be the case. Generally, the
messages that are exchanged are not stored, but this also need not be
the case. IM differs from email in common usage in that instant
messages are usually grouped together into brief live conversations,
consisting of numerous small messages sent back and forth.
Instant messaging as a service has been in existence within intranets
and IP networks for quite some time. Early implementations include
zephyr [8], the unix talk application, and IRC. More recently, IM
has been used as a service coupled with presence and buddy lists;
that is, when a friend comes online, a user can be made aware of this
and have the option of sending the friend an instant message. The
protocols for accomplishing this are all proprietary, which has
seriously hampered interoperability.
The integration of instant messaging, presence, and session-oriented
communications is very powerful. The Session Initiation Protocol
(SIP) [1]provides mechanisms that are useful for presence
applications, and for session-oriented communication applications,
but not for intant messages.
This document proposes an extension method for SIP called the MESSAGE
method. MESSAGE requests normally carry the instant message content
in the request body.
RFC2778 [7]and RFC2779 [6]give a model and requirements for presence
and instant messaging protocols. The MESSAGE method is intended to
meet the instant messaging requirements therein.
2. Overview of Operation
When one user wishes to send an instant message to another, the
sender formulates and issues a SIP request using the new MESSAGE
method defined by this document. The request URI of this request
will normally be the "address of record" for the recipient of the
instant message, but if may be a device address in situations where
the client has current information about the recipients location.
For example, the client could be coupled with a presence system that
supplies an up to date device contact for a given address of record.
The body of the request will contain the message to be delivered.
This body can be of any MIME type, including message/cpim. [4]
The request may traverse a set of SIP proxies, using a variety of
transports, before reaching its destination. The destination for
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each hop is located using the address resolution rules detailed in
the Common Profile for Instant Messaging (CPIM) [3] and SIP
specifications. During traversal, each proxy may rewrite the request
URI based on available routing information.
Provisional and final responses to the request will be returned to
the sender as with any other SIP request. Normally, a 200 OK
response will be generated by the user agent of the request's final
recipient. Note that this indicates that the user agent accepted the
message, not that the user has seen it.
MESSAGE requests do not establish dialogs.
3. UAC Processing
Unless stated otherwise in this document, MESSAGE requests and
associated responses are constructed according to the rules in
section 8.1 of the SIP specification. [1]
All UAs which support the MESSAGE method MUST be prepared to send and
receive MESSAGE requests with a body of type text/plain. They MAY
send bodies of type message/cpim.
MESSAGE requests do not initiate dialogs. User Agents MUST not
insert contact headers into MESSAGE requests.
A UAC MAY associate a MESSAGE request with an existing dialog. If a
MESSAGE request is sent within a dialog, it is "associated" with any
media session or sessions associated with that dialog.
If the UAC receives a 200 OK response to a MESSAGE request, it may
assume the message has been delivered to the final destination. It
MUST NOT assume that the recipient has actually read the instant
message. If the UAC receives a 202 Accepted response, the message
has been delivered to a gateway, store and forward server, or some
other service that may eventually deliver the message. In this case,
the UAC MUST NOT assume the message has been delivered to the final
destination. If confirmation of delivery is required for a message
that has been responded to with a 202 Accepted, that confirmation
must be delivered via some other mechanism, which is beyond the scope
of this specification.
Note that a downstream proxy could fork a MESSAGE request. If this
occurs, the forking proxy will forward one final response upstream,
even though it may receive multiple final responses. The UAC will
have no way to detect whether or not a fork occurs. Therefore the
UAC MUST NOT assume that a given final response represents the only
UAS that receives the request. For example, multiple branches of a
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fork could have resulted in 2XX class responses. Even though the UAC
only sees one of those responses, the request has in fact been
received by the second device as well.
4. Use of Instant Message URIs
An instant inbox may be most generally referenced by an Instant
Message URI [3] in the form of "im:user@domain". IM URIs are
abstract, and MUST eventually be translated to concrete, protocol-
dependent URI using the method described in the CPIM specification.
[3]
If a UA is presented with an IM URI as the address for an instant
message, it SHOULD resolve it to a SIP URI, and place the resulting
URI in the Request-URI of the MESSAGE request before sending. If the
UA is unable to resolve the IM URI, it MAY place the IM URI in the
Request-URI, thus delegating the resolution to a downstream device
such as proxy or gateway. Performing this translation as early as
possible allows SIP proxies, which may be unaware of the im:
namespace, to route the requests normally.
MESSAGE requests also contain logical identifiers of the sender and
intended recipient, in the form of the From and To headers. These
identifiers SHOULD contain SIP (or SIPS) URIs, but MAY include IM
URIs if the SIP URIs are not known at the time of request
construction.
Record-Route and Route headers MUST NOT contain IM URLs. These
headers contain concrete SIP or SIPS URLs according to the rules of
SIP. [1]
5. Proxy Processing
Proxies route MESSAGE requests according to the rules of SIP [1]for
proxy routing of requests that do not initate dialogs. Note that the
MESSAGE request MAY fork; this allows for delivery of the message to
several possible terminals where the user might be. A proxy forking
a MESSAGE request follows the normal SIP rules for forking a non-
invite request. In particular, even if the fork results in multiple
successful deliveries, the forking proxy will only forward one final
response upstream.
6. UAS Processing
A UAS that receives a MESSAGE request processes it following the
rules of SIP. [1]
A UAS receiving a MESSAGE request SHOULD respond with a final
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response immediately. Note, however, that the UAS is not obliged to
display the message to the user either before or after responding
with a 200 OK. That is, a 200 OK response does not necessarily mean
the user has read the message.
A 2XX class response to a MESSAGE request MUST NOT contain a body. A
UAS MUST NOT insert a contact header into a 2XX class response.
A UAS which is, in fact, a message relay, storing the message and
forwarding it later on, or forwarding it into a non-SIP domain,
SHOULD return a 202 (Accepted) [5] response indicating that the
message was accepted, but end to end delivery has not been
guaranteed.
A 4XX or 5XX class response indicates that the message was not
delivered successfully. A 6XX response means it was delivered
successfully, but refused.
A UAS that supports the MESSAGE method MUST be prepared to receive
and interpret body types of "text/plain" and "message/cpim". [4]
7. Caller Preferences
User agents SHOULD add the "methods" tag defined in the caller
preference [2] specification to Contact headers with SIP URIs placed
in REGISTER requests, indicating support for the MESSAGE method.
Other elements of caller preferences MAY be supported. For example:
REGISTER sip:dynamicsoft.com SIP/2.0
Via: SIP/2.0/UDP mypc.dynamicsoft.com
To: sip:jdrosen@dynamicsoft.com
From: sip:jdrosen@dynamicsoft.com
Call-ID: asidhasd@1.2.3.4
CSeq: 39 REGISTER
Contact: sip:jdrosen@im-pc.dynamicsoft.com;methods="MESSAGE"
Content-Length: 0
Registrar/proxies which wish to offer IM service SHOULD implement the
proxy processing defined in the caller preferences specification .
8. Congestion Control
Existing IM services have a history of very high volume usage. There
is potential that when a SIP infrastructure is shared between call
signalling and instant messaging, the IM traffic will interfere with
call signalling traffic. Congestion control in general is an issue
that should be addressed at the SIP specification level rather than
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for an individual method. But since the traffic patterns are likely
to be different for MESSAGE than for most other methods, it makes
sense to give MESSAGE special consideration.
Whenever possible, MESSAGE requests SHOULD be sent over transports
that implement end-to-end congestion control, such as TCP or SCTP.
9. Method Definition
This specification defines a new SIP method, MESSAGE. The BNF for
this method is:
MESSAGEm = %x4D.45.53.53.41.47.45 ;MESSAGE in caps
As with all other methods, the MESSAGE method name is case sensitive.
Tables 1 and 2 extend Tables 2 and 3 of SIP [1]by adding an
additional column, defining the headers that can be used in MESSAGE
requests and responses.
Header Field where proxy MESSAGE
__________________________________________
Accept R -
Accept 2xx -
Accept 415 m*
Accept-Encoding R -
Accept-Encoding 2xx -
Accept-Encoding 415 m*
Accept-Language R -
Accept-Language 2xx -
Accept-Language 415 m*
Alert-Info R -
Alert-Info 180 -
Allow R o
Allow 2xx o
Allow r o
Allow 405 m
Authentication-Info 2xx o
Authorization R o
Call-ID c r m
Call-Info ar o
Contact R -
Contact 1xx -
Contact 2xx -
Contact 3xx o
Contact 485 o
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Content-Disposition o
Content-Encoding o
Content-Language o
Content-Length ar t
Content-Type *
CSeq c r m
Date a o
Error-Info 300-699 a o
Expires o
From c r m
In-Reply-To R o
Max-Forwards R amr m
Organization ar o
Table 1: Summary of header fields, A--O
Header Field where proxy MESSAGE
__________________________________________
Priority R ar o
Proxy-Authenticate 407 ar m
Proxy-Authenticate 401 ar o
Proxy-Authorization R dr o
Proxy-Require R ar o
Record-Route ar -
Reply-To o
Require ar c
Retry-After 404,413,480,486 o
500,503 o
600,603 o
Route R adr o
Server r o
Subject R o
Timestamp o
To c(1) r m
Unsupported 420 o
User-Agent o
Via R amr m
Via rc dr m
Warning r o
WWW-Authenticate 401 ar m
WWW-Authenticate 407 ar o
(1): copied with possible addition of tag
Table 2: Summary of header fields, P--Z
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A MESSAGE request MAY contain a body, using the standard MIME headers
to identify the content.
10. Example Messages
An example message flow is shown in Figure 1. The message flow shows
an initial IM sent from User 1 to User 2, both users in the same
domain, "domain", through a single proxy.
| F1 MESSAGE | |
|--------------------> | F2 MESSAGE |
| | ----------------------->|
| | |
| | F3 200 OK |
| | <-----------------------|
| F4 200 OK | |
|<-------------------- | |
| | |
| | |
| | |
User 1 Proxy User 2
Figure 1: Example Message Flow
Message F1 looks like:
MESSAGE sip:user2@domain.com SIP/2.0
Via: SIP/2.0/UDP user1pc.domain.com
From: sip:user1@domain.com
To: sip:user2@domain.com
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Type: text/plain
Content-Length: 18
Watson, come here.
User1 forwards this message to the server for domain.com. The proxy
receives this request, and recognizes that it is the server for
domain.com. It looks up user2 in its database (built up through
registrations), and finds a binding from sip:user2@domain.com to
sip:user2@user2pc.domain.com. It forwards the request to user2. The
resulting message, F2, looks like:
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MESSAGE sip:user2@domain.com SIP/2.0
Via: SIP/2.0/UDP proxy.domain.com
Via: SIP/2.0/UDP user1pc.domain.com
From: sip:user1@domain.com
To: sip:user2@domain.com
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Type: text/plain
Content-Length: 18
Watson, come here.
The message is received by user2, displayed, and a response is
generated, message F3, and sent to the proxy:
SIP/2.0 200 OK
Via: SIP/2.0/UDP proxy.domain.com
Via: SIP/2.0/UDP user1pc.domain.com
From: sip:user1@domain.com
To: sip:user2@domain.com;tag=ab8asdasd9
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Length: 0
Note that most of the header fields are simply reflected in the
response. The proxy receives this response, strips off the top Via,
and forwards to the address in the next Via, user1pc.domain.com, the
result being message F4:
SIP/2.0 200 OK
Via: SIP/2.0/UDP user1pc.domain.com
From: sip:user1@domain.com
To: sip:user2@domain.com;tag=ab8asdasd9
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Length: 0
11. Security Considerations
In normal usage, most SIP requests are used to setup and modify
communication sessions. The actual communication between
participants happens in the media sessions, not in the SIP requests
themselves. The MESSAGE method changes this assumption; MESSAGE
requests normally carry the actual communication between participants
as payload. This implies that MESSAGE requests have a greater need
for security than most other SIP requests. In particular, UAs that
support the MESSAGE request SHOULD support end-to-end authentication,
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body integrity, and body confidentiality mechanisms.
11.1 Outbound authentication
When local proxies are used for transmission of outbound messages,
proxy authentication is RECOMMENDED. This is useful to verify the
identity of the originator, and prevent spoofing and spamming at the
originating network.
11.2 SIPS URIs
The SIPS URI mechanism [1] allows a UA to assert that every hop must
occur over a secure connection. This provides some level of
integrity and privacy protection. However, this requires the users
to trust that each proxy in the request path is well-behaved, that
is, they do not violate the rules for routing SIPS URIs. Also, any
unencrypted bodies are fully exposed to the proxies.
Additionally, the possibility of a forking proxy allows a MESSAGE
request to be delivered to additional endpoints without the knowledge
of the UAC. If only hop-by-hop protection is used, the users must
trust all proxies in the chain to not fork requests to unauthorized
destinations.
11.3 End-to-End Protection
UAs may provide end-to-end protection throught the use of S/MIME.
SIP allows the use of S/MIME to provide privacy and integrity
protection of message bodies. S/MIME also allows privacy protection
of SIP headers that are not read by proxies, and integrity
protection of headers that are not modified by proxies.
Due to the greater security requirements for MESSAGE requests, UAs
that support the MESSAGE method SHOULD support S/MIME.
11.4 Replay Prevention
To prevent the replay of old SIP requests, all signed MESSAGE
requests and responses SHOULD contain a Date header covered by the
message signature. Any message with a date older than several
minutes in the past, or which is more than several minutes in the
future, should be answered with a 400 (Incorrect Date or Time)
message, unless such messages arrive repeatedly from the same source,
in which case they MAY be discarded without sending a response.
Obviously, this replay attack prevention mechanism does not work for
devices without clocks.
Note that there are situations where an stale Date header is normal.
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For example, the MESSAGE request may have been stored in a store and
forward server while the recipient was offline. When the recipient
returns, that server might then forward the message. Final receipt
of the message would then occur some time after it was originally
sent.
If a UAS receives a stale message that can be confirmed to have come
from a known store and forward server (perhaps over a TLS
connection), it makes sense for it to accept the message normally.
Also, if one or more stale messages arrive shortly after an offline
period, the UAS MAY accept the message, but SHOULD warn the user that
there is a risk the message has been replayed.
11.5 Using message/cpim bodies
The message/cpim format [4] allows for the S/MIME protection of
metadata in addition to the message payload itself. In many cases,
this metadata is redundant with SIP headers. Still, message/cpim
adds value in that the protection of metadata can extend across
protocol bounderies. For example, a signed message/cpim body can
provide sender authentication using the message/cpim From header,
even if the message crosses a gateway to another CPIM compliant
instant message service that does not understand SIP headers.
Therefore UAs SHOULD use the message/cpim format when protecting
bodies using S/MIME. UAs may choose not to use message/cpim if they
have knowledge that the message recipient, and all points between,
are SIP devices.
12. IANA Considerations
This specification registers the MESSAGE method in the http://
www.iana.org/assignments/sip-parameters/Method registry, according to
the following information:
MESSAGE [RFCXXXX]
13. Changes to This Document
13.1 Changes introduced in draft-ietf-sip-message-03
Updated BNF to escape all characters in "MESSAGE". Fixed a few typos
13.2 Changes introduced in draft-ietf-sip-message-02
Updated references to the SIP specification.
Removed text that was redundant with SIP and CPIM documents.
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Split references into normative and informational.
Added additional text on the issues of forking MESSAGE requests.
Added text on the meaning of 202 responses.
Updated tables 1 and 2 to reflect the current SIP specification.
Added IANA consideration section registering the MESSAGE method.
Removed terminology section because it was completely redundant with
the SIP specification and RFC2779.
Added text to recommend that IM URIs be resolved as early as
possible.
Removed discussion of using In-Reply-To for threading. This will be
addressed in a separate "usage" draft, probably in the SIMPLE working
group.
Removed analysis of RFC 2779 requirements--this may be moved to the
usage draft.
Expanded the abstract section.
Removed "sales pitch" from the introduction.
Updated the Security Consideration section to include latest SIP
security features.
Added text to Security Considerations concerning stale Date headers
in offline messages.
Several editorial and organizational changes.
13.3 Changes introduced in draft-ietf-sip-message-01
The CPIM mapping section has been removed to a separate document.
The references to the IMPP CPIM drafts have been updated to track
newer versions.
13.4 Changed Introduced in draft-ietf-sip-message-00
The draft name changed (again) due to its move to the SIP working
group.
The draft now clarifies that, while MESSAGE requests do not establish
dialogs, user agents may group messages into conversation threads.
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The draft clarifies the intend that all implementations must handle
message/cpim body parts.
References to PGP encryption in SIP have been removed.
Open Issue concerning mapping between URI schemes at a CPIM compliant
gateway device has been closed. This draft treats such mapping as a
matter of local policy.
Added text for the congestion control section and removed related
open issues.
13.5 Changes Introduced in draft-ietf-simple-im-01
This version removes the idea of implicit sessions created by MESSAGE
requests. MESSAGE requests are now completely stateless in
themselves.
The version also some open issues: Bodies are not allowed in
responses; an Accept header on a 415 response includes body types
nested inside message/cpim bodies, all IM UAs MUST be able to receive
message/cpim.
This draft introduces a new section for CPIM mapping. The authors
expect this section will need further work to complete.
13.6 Changes Introduced in draft-ietf-simple-im-00
The draft name changed to reflect its status as a SIMPLE working
group item. This version introduces no other changes.
13.7 Changes Introduced in draft-rosenberg-impp-im-01
This submission serves to track transition of the work on a SIP
implementation of IM to the newly formed SIMPLE working group. It
endeavors to capture the progress made in IMPP since the original
submission (in particular, including the im: URI and the message/cpim
body) and detail a set of open issues for the SIMPLE working group to
address.
To support those goals, a great deal of the background and motivation
material in the original text has been shortened or removed.
14. Acknowledgments
The authors would like to thank the following people for their
support of the concept of SIP for IM, support for this work, and for
their useful comments and insights:
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Jon Peterson Neustar
Sean Olson Microsoft
Adam Roach dynamicsoft
Billy Biggs University of Waterloo
Stuart Barkley UUNet
Mauricio Arango SUN
Richard Shockey Neustar
Jorgen Bjorker Hotsip
Henry Sinnreich MCI Worldcom
Ronald Akers Motorola
Torrey Searle Indigo Software
Rohan Mahy Cisco
Christian Groves Ericsson
Normative References
[1] Rosenberg, J. and H. Schulzrinne, "SIP: Session Initiation
Protocol", draft-ietf-sip-rfc2543bis-09 (work in progress),
February 2002.
[2] Rosenberg, J. and H. Schulzrinne, "SIP Caller Preferences and
Callee Capabilities", draft-ietf-sip-callerprefs-05 (work in
progress), November 2001.
[3] Crocker, D., Diacakis, A., Mazzoldi, F., Huitema, C., Klyne, G.,
Rose, M., Rosenberg, J., Sparks, R. and H. Sugano, "A Common
Profile for Instant Messaging (CPIM)", draft-ietf-impp-cpim-02
(work in progress), February 2001.
[4] Atkins, D. and G. Klyne, "Common Presence and Instant Messaging
Message Format", draft-ietf-impp-cpim-msgfmt-06 (work in
progress), February 2001.
[5] Roach, A., "SIP-Specific Event Notification", draft-ietf-sip-
events-05 (work in progress), March 2002.
Informational References
[6] Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging /
Presence Protocol Requirements", RFC 2779, February 2000.
[7] Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
Instant Messaging", RFC 2778, February 2000.
[8] DellaFera, C., Eichin, M., French, R., Jedlinski, D., Kohl, J.
and W. Sommerfeld, "The Zephyr notification service", in USENIX
Winter Conference (Dallas, Texas), Feb. 1988.
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Authors' Addresses
Ben Campbell
dynamicsoft
5100 Tennyson Parkway
Suite 1200
Plano, TX 75024
EMail: bcampbell@dynamicsoft.com
Jonathan Rosenberg
dynamicsoft
72 Eagle Rock Avenue
First Floor
East Hanover, NJ 07936
EMail: jdrosen@dynamicsoft.com
Dean Willis
dynamicsoft
5100 Tennyson Parkway
Suite 1200
Plano, TX 75024
EMail: dwillis@dynamicsoft.com
Robert J. Sparks
dynamicsoft
5100 Tennyson Parkway
Suite 1200
Plano, TX 75024
EMail: rsparks@dynamicsoft.com
Henning Schulzrinne
Columbia University
M/S 0401
1214 Amsterdam Ave.
New York, NY 10027-7003
EMail: schulzrinne@cs.columbia.edu
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Jonathan Lennox
Columbia University
M/S 0401
1214 Amsterdam Ave.
New York, NY 10027-7003
EMail: lennox@cs.columbia.edu
Christian Huitema
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
EMail: huitema@microsoft.com
Bernard Aboba
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
EMail: bernarda@microsoft.com
David Gurle
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
EMail: dgurle@microsoft.com
David Oran
Cisco Systems
170 West Tasman Dr.
San Jose, CA 95134
EMail: oran@cisco.com
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