Internet Engineering Task Force V.Bajaj
K.Laha
Internet Draft Hughes Software Systems
Document: Bill Foster
draft-manyfolks-megaco-caspackage-00.txt
Cisco Systems
Michael Brown
Wendy Bothwell
Nortel Networks
Category: Informational January 2001
Megaco/H.248 Basic CAS Packages
Status of this Memo
This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026 [1].
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-
Drafts. Internet-Drafts are draft documents valid for a maximum of
six months and may be updated, replaced, or obsoleted by other
documents at any time. It is inappropriate to use Internet- Drafts
as reference material or to cite them other than as "work in
progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
1. Abstract
This document is work in progress and defines Basic Channel
Associated Signaling (CAS) and R1 packages and supplemental CAS
packages in association with the Megaco/H.248 Protocol that can be
used to control a Media Gateway (MG) from an external controller,
called a Media Gateway controller (MGC). It is intended to satisfy
the requirements in section 12 of the Megaco/H.248 requirement
document [2].
2. 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 [3].
manyfolks Informational -- Expires June 14, 2001 1
Megaco/H.248 Basic CAS Package January 2001
3. Document Organization
The subsequent portion of this draft is organized into the
following major sections:
* Introduction
* Assumptions and Partitioning
* Description of the Basic CAS package
* Description of the Robbed Bit Signaling package
* Description of the Operator Services and Emergency Services
package
* Description of the Operator Services Extension package
* References
* Author's Addresses
* Appendix showing call flows
4. Introduction
The Basic CAS (Channel Associated Signaling) Package can be used
for single stage dialing applications such as interconnect to PBX's
using either immediate start, delay start or wink start signaling
with either MF, DTMF or dial-pulse (DP) digits used for
addressing. It can also used for inter-exchange signaling. This
includes R1 as well as Feature Group D (FGD) MF signaling single
stage dialing (FGD terminating protocol). It also provides the
basis for multi-stage dialing applications such as FGD Operator
Services and inter-exchange signaling [4]. While this package is
intended meet the requirements of any variant of CAS, it may be
necessary in the future to development extensions to the package.
In addition, the package can be applied to analog trunking
applications such as:
E&M analog trunks
R1 analog trunks
The RBS (Robbed Bit Signaling) Package, Operator Services and
Emergency Services Package and the Operator Services Extension
Package can be used to provide functionality required in addition
to the Basic CAS Package, such as operator and emergency services
capabilities or multi-stage Feature Group D inter-exchange
signaling.
5. Assumptions and Partitioning
The following approach was used in providing functionality in the
Basic CAS Package:
The package provides some basic supervisory signaling
manyfolks Informational -- Expires June 14, 2001 2
Megaco/H.248 Basic CAS Package January 2001
It provide an abstract event for "start-dialing"/"proceed-to-send"
which is non-specific to the type of CAS.
Used in conjunction with MF and DTMF detection and generation
packages, it provides the ability to do digit collection and
outpulsing of both MF and DTMF digits.
It provides error event reporting.
For some applications, the Basic CAS package provides all of the
functionality needed to satisfy the interface. In other cases (e.g.
operator services), additional supplementary packages may be needed
to meet the complete interface requirements. This internet draft
includes three supplementary packages which may be used to provide
additional functionality required by some interfaces:
The Robbed Bit Signaling package provides basic rbs supervisory
signaling that is required in addition to the Basic CAS package.
The Operator Services and Emergency Services package provides
supervisory signaling that is specific to both Operator Services
and Emergency Services.
The Operator Services Extension package provides supervisory
signaling that is specific to Operator Services and is required in
addition to the Operator Services and Emergency Services package.
6. Basic CAS Package Description
6.1 Package
Package Name: Basic CAS Package
Package ID: bcas (To be allocated through IANA)
Description: This package provides basic event and signal handling
for terminations that supporting CAS Signaling between the
Media Gateway and either the PSTN network or a PBX.
Version: 1
Extends: None
6.2 Properties
The MG has a provisioned value for each of the following
properties. The MG uses the provisioned value by default.
However, it is necessary, for some CAS signaling protocols,
to change these values for a call.
Property Name: seize signal validation time
PropertyID: sztim
Description: Specifies the minimum duration for which the "seizing"
signal must persist for the same to be reported as an event.
Type: integer, in milliseconds
Possible Values: 0 and up
manyfolks Informational -- Expires June 14, 2001 3
Megaco/H.248 Basic CAS Package January 2001
Defined In: TerminationState
Characteristics: Read/Write
Property Name: start dialing timeout
PropertyID: sdto
Description: Specifies the timer for the receipt of the "start
dialing" signal.
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
Property Name: answer timeout
PropertyID: ansto
Description: Specifies the timer for the receipt of the "answer"
signal.
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
Property Name: answer signal validation time
PropertyID: anstim
Description: Specifies the minimum duration for which the "answer"
signal must persist for the same to be reported as an event.
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
Property Name: clear signal validation time
PropertyID: clrtim
Description: Specifies the minimum duration for which the gateway,
if behaving as an incoming end, validates the "clear-
forward" signal (or on-hook).
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
6.3 Events
6.3.1
Event Name: Seizure
EventID: sz (0x0001)
Description: The Seizure event shall be reported when an incoming
"Seizing" signal occurs on the termination and an events
descriptor is activated that requests the Seizure event. The
line signal condition against which the "Seizing" signal is
verified is provisioned in the MG.
manyfolks Informational -- Expires June 14, 2001 4
Megaco/H.248 Basic CAS Package January 2001
EventsDescriptor Parameters:
none defined for this package
ObservedEventsDescriptor Parameters:
none defined by this package
6.3.2
Event Name: Start Dialing
EventID: sd (0x0002)
Description: The "Start Dialing" event indicates out-pulsing should
begin. For R1 interfaces, the event is reported when the
"start dialing"/"proceed to send" signal occurs. For wink
start trunks, the "Start Dialing" event is reported when the
trailing edge of the wink-start signal occurs. For immediate
start trunks, the "Start Dialing" event is provided by the
media gateway as an immediate response to the request for
the that event from the MGC. This allows the MGC to
experience an identical interface regardless of trunk type.
EventsDescriptor Parameters:
none defined for this package
ObservedEventsDescriptor Parameters:
none defined by this package
6.3.3
Event Name: Answer
EventID: ans (0x0003)
Description: The Answer event shall be reported when an incoming
line signal "Answer" occurs on the termination and an events
descriptor is activated that requests the Answer event. The
line signal condition against which the "Answer" signal is
verified is provisioned in the MG.
EventsDescriptor Parameters:
none defined by this package
ObservedEventsDescriptor Parameters:
none defined by this package
6.3.4
Event Name: Clear Forward
EventID: cf (0x0004)
Description: This event applies to an incoming interface and is
reported when a "Clear" signal occurs on the termination and
an events descriptor is activated that requests the Clear
Forward event. For an R1 interface, the Clear Forward event
shall be reported when a "Clear-forward" line signal occurs
on the termination. For robbed bit signaling digital
interfaces, it corresponds to an "on-hook" indication on the
termination. The condition against which the signal is
verified is provisioned in the MG.
EventsDescriptor Parameters:
manyfolks Informational -- Expires June 14, 2001 5
Megaco/H.248 Basic CAS Package January 2001
none defined by this package
ObservedEventsDescriptor Parameter:
none defined by this package
Event Name: Clear Back
EventID: cb (0x0005)
Description: This event applies to an outgoing interface and is
reported when a "Clear" signal occurs on the termination and
an events descriptor is activated that requests the Clear
Back event. For an R1 interface, the Clear Back event shall
be reported when a "Clear-back" line signal occurs on the
termination. For robbed bit signaling digital interfaces, it
corresponds to an "on-hook" indication on the termination.
The condition against which the signal is verified is
provisioned in the MG.
EventsDescriptor Parameters:
none defined by this package
ObservedEventsDescriptor Parameter:
none defined by this package
6.3.5
Event Name: CAS Failure
EventID: casf (0x0006)
Description: Reports general CAS failures associated with this
package.
EventsDescriptor Parameters:
none defined by this package
ObservedEventsDescriptor Parameters:
Parameter Name: Error code
ParameterID: ec (0x0001)
Description: describes the failure reason
Type: enumeration
Possible Values:
"ULS" (0x0001) Unexpected line signal
"LTO" (0x0002) Line signal timeout
"RTO" (0x0003) Register signal timeout
"SME" (0x0004) Protocol State machine malfunction
"SDO" (0x0005) Start Dialing Timeout
"ANO" (0x0006) Answer Timeout
"ADR" (0x0007) Error during outpulsing
6.4 Signals
Parameters: None
6.4.1
Signal Name: Seizure
SignalID: sz (0x0001)
manyfolks Informational -- Expires June 14, 2001 6
Megaco/H.248 Basic CAS Package January 2001
Description: Applies a "Seizing" signal on the termination. The
line signal that is actually sent on the physical
termination is provisioned in the MG.
Signal Type: (BR) Brief
Duration: Not applicable
Additional Parameters: None
6.4.2
Signal Name: Answer
SignalID: ans (0x0002)
Description: Applies an "Answer" signal on the termination. The
line condition that is actually sent on the physical
termination is provisioned in the MG.
Signal Type: (BR) Brief
Duration: Not applicable
Additional Parameters: None
6.4.3
Signal Name: Clear Forward
SignalID: cf (0x0003)
Description: This signal applies to an outgoing interface and is
used to clear a call in the forward direction. The signal
type that is actually sent on the physical termination is
provisioned in the MG.
Signal Type: (BR) Brief
Duration: Provisioned
Signal Name: Clear Back
SignalID: cb (0x0004)
Description: This signal applies to an incoming interface and is
used to clear a call in the backward direction. The signal
type that is actually sent on the physical termination is
provisioned in the MG.
Signal Type: (BR) Brief
Duration: Provisioned
6.4.4.
Signal Name: Address
SignalID: addr (0x0005)
Description: Applies the address signals in the form of either
DTMF, dial-pulse or MF-tones on the trunk. The actual
frequency, cadence, duration and amplitude values for the
multi-frequency tones that convey the address information
are provisioned in the MG.
Signal Type: (BR) Brief
Duration: Provisioned
Additional Parameters:
Parameter Name: Digit String
ParameterID: ds (0x0001)
manyfolks Informational -- Expires June 14, 2001 7
Megaco/H.248 Basic CAS Package January 2001
Description: The digit string that needs to be sent as address
signals.
Type: string of digits.
Possible Values: a sequence of the characters "0" through "9"
as well as "A" and "E" ("A" and "E" used for MF signaling -
refer to the symbols defined for the digit map in the MF
Tone Detection package.
Parameter Name: Address Delay
ParameterID: ad (0x0002)
Description: Specifies a timed delay that is applied prior to
signaling the address. The address delay is optional. The MG
has a provisioned value by default. If the address delay
parameter is not provided, the MG uses the provisioned
value.
Type: integer, in milliseconds
Possible Values: 0 and up
6.5 Statistics
none
6.6 Procedures
6.6.1 Glare Procedures
Gateways may have a configurable glare bit on a per-DS0 basis that
can be set to indicate whether the gateway is the controlling or
non-controlling "switch".
In the case of PBX interconnect, PBXs are either pre-configured or
can be configured to behave as non-controlling switches. In this
case if they see an off-hook that exceeds allowable wink length,
they will attach a receiver, go on-hook, and await digits for a new
call. Meanwhile the PBX will retry its original call on another
trunk.
In the case where the DS0 is configured for the non-controlling
switch, the gateway will indicate a glare occurrence by reporting a
seizure event to the MGC. Upon receipt of the seizure event, the
MGC begins procedures to back down on the outgoing call attempt and
begins procedures to process the incoming call attempt.
If the gateway behaves like a controlling switch, when glare is
detected, the gateway will wait for up to some timeout value
(default value of 4 seconds) until the incoming off-hook changes to
an on-hook state at which time it will start out-pulsing in the
normal manner. If the timeout occurs before the state change to on-
hook occurs, the far end has refused to back down. This may occur
if both ends of the interface are provisioned as the controlling
switch. In this case, when the timeout occurs, the gateway reports
the seizure event to the MGC. The MGC, upon receipt of the notify
with seizure event, begins procedures to back down on the outgoing
manyfolks Informational -- Expires June 14, 2001 8
Megaco/H.248 Basic CAS Package January 2001
call attempt and begins procedures process the incoming call
attempt.
It is possible for internal glare to occur between the MGC and the
gateway. With internal glare, the gateway detects a seizure event
on the DS0, signals a start dial and reports the seizure event to
the MGC. At the same time the gateway reports the seizure event to
the MGC, the MGC sends a modify to the gateway requesting the
gateway signal a seizure on the DS0. In this case, the start dial
has already been signaled by the gateway in response to the
incoming seizure. Therefore the MGC must back down on the outgoing
call attempt. The gateway, upon receipt of the modify request to
signal a seizure, recognizes internal glare has occurred and takes
no action on the modify request. The MGC, upon receipt of the
notify with seizure event, recognizes internal glare has occurred
and begins procedures to back down on the outgoing call attempt and
begins procedures to process the incoming call attempt.
6.6.2 Timestamp Procedures
Inclusion of a timestamp in the ObservedEvents descriptor is
mandatory for the basic CAS package. The timestamp reflects the
detection time for the event and may be used by services (e.g.
automatic message accounting) on the MGC.
7. Robbed Bit Signaling Package
7.1 Package
PackageID: rbs
Description: This package defines events and signals that are
specific to robbed bit signaling and are required in
addition to the base CAS functionality provided by the bcas
package.
Version: 1
Extends: None
7.2 Properties
The MG has a provisioned value for each of the following
properties. The MG uses the provisioned value by default. However,
it is necessary, for some signaling protocols, to change these
values for a call.
Property Name: Pulse Generation Duration
PropertyID: psgen
Description: Specifies the duration for a pulse signal.
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
manyfolks Informational -- Expires June 14, 2001 9
Megaco/H.248 Basic CAS Package January 2001
Property Name: Minimum Pulse Detection Duration
PropertyID: minpsdet
Description: Specifies the minimum duration for detecting a pulse.
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
Property Name: Maximum Pulse Detection Duration
PropertyID: maxpsdet
Description: Specifies the maximum duration for detecting a pulse.
Type: integer, in milliseconds
Possible Values: 0 and up
Defined In: TerminationState
Characteristics: Read/Write
7.3 Events
Event Name: Pulse Off
EventID: psoff (0x0001)
Description: The MG detects and reports a timed transition from on-
hook to off-hook (leading edge) to on-hook (trailing edge).
The parameter "pulse timeout" can be optionally included to
specify a timeout for the receipt of the pulse. A default
value for the timer is provisioned on the MG. The minimum
and maximum duration of the pulse are defined by the Minimum
Pulse Detection Duration and Maximum Pulse Detection
Duration properties respectively.
EventsDescriptor Parameters:
Parameter Name: Pulse Timeout
ParameterID: psto
Description: Specifies the timer for the receipt of the pulse.
Type: integer, in milliseconds
Possible values: 0 and up
ObservedEventsDescriptor Parameters: None
Event Name: Pulse On
EventID: pson (0x0002)
Description: The MG detects and reports a timed transition from
off-hook to on-hook (leading edge) to off-hook (trailing
edge). The parameter "pulse timeout" can be optionally
included to specify a timeout for the receipt of the pulse.
A default value for the timer is provisioned on the MG. The
minimum and maximum duration of the pulse are defined by the
Minimum Pulse Detection Duration and Maximum Pulse Detection
Duration properties respectively.
EventsDescriptor Parameters:
Parameter Name: Pulse Timeout
ParameterID: psto
manyfolks Informational -- Expires June 14, 2001 10
Megaco/H.248 Basic CAS Package January 2001
Description: Specifies the timer for the receipt of the pulse.
Type: integer, in milliseconds
Possible values: 0 and up
ObservedEventsDescriptor Parameters: None
Event Name: RBS Failure
EventID: rbsfail (0x0003)
Description: Reports a failure condition when an events descriptor
is activated requesting the rbs failure event.
EventsDescriptor Parameters: None.
ObservedEventsDescriptor Parameters:
Parameter Name: Error Code
ParameterID: ec
Description: describes the failure reason
Type: enumeration
Possible Values:
"psto" Timeout waiting for a pulse event
7.4 Signals
Signal Name: Pulse Off-hook
SignalID: psoff (0x0001)
Description: The MG signals a timed transition from on-hook to off-
hook (leading edge) to on-hook (trailing edge).
Signal Type: Brief
Duration: Defined by Pulse Generation Duration property.
Additional Parameters: None
Signal Name: Pulse On-hook
SignalID: pson (0x0002)
Description: The MG signals a timed transition from off-hook to on-
hook (leading edge) to off-hook (trailing edge).
Signal Type: Brief
Duration: Defined by Pulse Generation Duration property.
Additional Parameters: None
7.5 Statistics
None.
7.6 Procedures
7.6.1 Timestamp Procedures
Inclusion of a timestamp in the ObservedEvents descriptor is
mandatory for the RBS package. The timestamp reflects the detection
time for the event and may be used by services (e.g. automatic
message accounting) on the MGC.
manyfolks Informational -- Expires June 14, 2001 11
Megaco/H.248 Basic CAS Package January 2001
8. Operator Services and Emergency Services Package
8.1 Package
PackageID: oses
Description: This package defines CAS events and signals that are
required for both Operator Services and Emergency Services.
Version: 1
Extends: None
8.2 Properties
None.
8.3 Events
Event Name: Ringback
EventID: rgbk (0x0001)
Description: The ringback event is reported when a ringback signal
is detected and an events descriptor is activated requesting
the ringback event. The type of ringback signal and
characteristics of the ringback signal are provisioned on
the MG.
EventsDescriptor Parameters: None
ObservedEventsDescriptor Parameters: None
8.4 Signals
Signal Name: Ringback
SignalID: rgbk (0x0001)
Description: Applies a ringback signal on the termination. The type
of ringback signal and characteristics of the ringback
signal are provisioned on the MG.
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
Signal Name: Calling Party On-hook
SignalID: cpon (0x0002)
Description: Applies an onhook signal on the termination. This
signal is used when the the calling party's on-hook status
must be signaled to the operator service or emergency
service switch.
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
8.5 Statistics
None.
manyfolks Informational -- Expires June 14, 2001 12
Megaco/H.248 Basic CAS Package January 2001
8.6 Procedures
None.
9. Operator Services Extension Package
9.1 Package
PackageID: osext
Description: This package defines CAS events and signals that are
specific to Operator Services and are required in addition
to the events and signals defined in the Operator Services
and Emergency Services package.
Version: 1
Extends: oses
9.2 Properties
None.
9.3 Events
Event Name: Recall
EventID: rcl (0x0002)
Description: The recall event is reported when a recall signal is
detected and an events descriptor is activated requesting the
recall event. The recall signal is a timed transition from
off-hook to on-hook (leading edge) to off-hook (trailing
edge). The duration of the timed transition is provisioned
on the MG.
EventsDescriptor Parameters: None
ObservedEventsDescriptor Parameters: None
Event Name: Coin Collect
EventID: cc (0x0003)
Description: The coin collect event is reported when a coin collect
signal is detected and an events descriptor is activated
requesting the coin collect event. The type of coin collect
signal and characteristics of the coin collect signal are
provisioned on the MG.
EventsDescriptor Parameters: None
ObservedEventsDescriptor Parameters: None
Event Name: Coin Return
EventID: cr (0x0004)
manyfolks Informational -- Expires June 14, 2001 13
Megaco/H.248 Basic CAS Package January 2001
Description: The coin return event is reported when a coin return
signal is detected and an events descriptor is activated
requesting the coin return event. The type of coin return
signal and characteristics of the coin return signal are
provisioned on the MG.
EventsDescriptor Parameters: None
ObservedEventsDescriptor Parameters: None
Event Name: Operator Attached
EventID: oa (0x0005)
Description: The operator attached event is reported when an
operator attached signal is detected and an events
descriptor is activated requesting the operator attached
event. The type of operator attached signal and
characteristics of the operator attached signal are
provisioned on the MG.
EventsDescriptor Parameters: None
ObservedEventsDescriptor Parameters: None
Event Name: Operator Released
EventID: or (0x0006)
Description: The operator released event is reported when an
operator released signal is detected and an events
descriptor is activated requesting the operator released
event. The type of operator released signal and
characteristics of the operator released signal are
provisioned on the MG.
EventsDescriptor Parameters: None
ObservedEventsDescriptor Parameters: None
9.4 Signals
Signal Name: Recall
SignalID: rcl (0x0003)
Description: Applies a timed transition from off-hook to on-
hook(leading edge) to off-hook (trailing edge).
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
Signal Name: Coin Collect
SignalID: cc (0x0004)
Description: Applies a coin collect signal on the termination. The
type of coin collect signal and characteristics of the coin
collect signal are provisioned on the MG.
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
Signal Name: Coin Return
manyfolks Informational -- Expires June 14, 2001 14
Megaco/H.248 Basic CAS Package January 2001
SignalID: cr (0x0005)
Description: Applies a coin return signal on the termination. The
type of coin return signal and characteristics of the coin
return signal are provisioned on the MG.
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
Signal Name: Operator Attached
SignalID: oa (0x0006)
Description: Applies an operator attached signal on the
termination. The type of operator attached signal and
characteristics of the operator attached signal are
provisioned on the MG.
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
Signal Name: Operator Released
SignalID: or (0x0007)
Description: Applies an operator released signal on the
termination. The type of operator released signal and
characteristics of the operator released signal are
provisioned on the MG.
Signal Type: Brief
Duration: Provisioned
Additional Parameters: None
9.5 Statistics
None.
9.6 Procedures
None.
10. References
[1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
[2] Draft Recommendation H.248 (February 2000), Temporary Document 37
(PLEN), Study Group 16, ITU-Telecommunication Standardization Sector
(to be issued as draft-ietf-megaco-protocol-07.txt)
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997
[4]Bellcore, Compatibility Information for Feature Group D Switched
Access Service, TR-NPL-000258, Issue 1, October 1985.
manyfolks Informational -- Expires June 14, 2001 15
Megaco/H.248 Basic CAS Package January 2001
11. Author's Addresses
Vikas Bajaj
Hughes Software Systems,Ltd.
Gurgaon,Haryana,India. 122015.
Ph: (91)-11-6346666.Ex-2804.
Fax: (91)-124-6342810 or 811.
mEmail: vbajaj@hss.hns.com.
Kushanava Laha
Hughes Software Systems,Ltd.
Gurgaon,Haryana,India. 122015.
Ph: (91)-11-6346666.Ex-3083
Email: klaha@hss.hns.com.
Bill Foster
Cisco Systems
170 West Tasman Dr
San Jose, CA 95134
Ph: (408) 527-8791
email: bfoster@cisco.com
Wendy Bothwell
Nortel Networks
4008 Chapel Hill Road
Research Triangle Park, NC USA 27709
Phone: (919) 991-7287
Email: Bothwell@nortelnetworks.com
C. Michael Brown
Nortel Networks
4008 Chapel Hill Road
Research Triangle Park, NC USA 27709
Phone: (919) 991-7767
Email: C.Michael.Brown@nortelnetworks.com
manyfolks Informational -- Expires June 14, 2001 16
Megaco/H.248 Basic CAS Package January 2001
12. Appendix A Call Flows
12.1 Basic Single-Stage MF or DTMF wink start or immediate start.
Origination:
PSTN/PBX MG MGC
<-- request to be notified seizure, digits
(digit map referenced)
--seize-> ---- "bcas/sz"-->
<-- seize ack and start dialing
--digits--> ---- "mfd/ce" -->
digits available
later when the other end answers:
<--off-hook-- <-- "bcas/ans" ---
Termination:
MGC MG PSTN/PBX
Start with embedded request to do "sz" and if start dialing ("sd")
occurs - automaticaally outpulse address:
---embedded request--> --- Seizure --->
<---- "bcas/sd"------- <-- wink/delay dial
followed by proceed to send
the MG as a reflex action to doing a seizure with request for "sd"
--- digits --->
Note: digits outpulsed
automatically because of the embedded request
12.2 EAOSS Termination - Telephone Company Operator Services Call :
The following call flow also applies to operator services signaling
interfaces defined prior to Exchange Access Operator Services
Signaling (EAOSS).
MGC MG PSTN
Start with a request to seize and report the start dialing event.
Option - can use an embedded request for the first set of address
digits.
---- request -----> ----seizure--->
<----"bcas/sd"----- <----wink-----
manyfolks Informational -- Expires June 14, 2001 17
Megaco/H.248 Basic CAS Package January 2001
Send a request to signal the first stage of digits (i.e. called) and
look for an answer. Signal Completion event can be (optionally) used
to indicate when outpulsing is complete. A timeout is specified for
the ansto property.
-- signal addr1 --> -----addr1---->
<------"g/sc"------
<----"bcas/ans"---- <-- off-hook--
Send a request to signal the second stage of digits (i.e. ANI).
Signal Completion event is used to indicate when outpulsing is
complete.
-- signal addr2 --> -----addr2---->
<------"g/sc"------
12.3 EAOSS Termination - IC/INC Operator Services Call indirect through
an Access Tandem (Overlap Outpulsing):
The following call flow also applies to Feature Group D (FGD)
signaling with the exception of an acknowledgment wink in place
of the off-hook hold request.
MGC MG PSTN
Start with a request to seize and report the start dialing event.
Option - can use an embedded request for the first set of address
digits.
---- request -----> ----seizure--->
<----"bcas/sd"----- <----wink-----
Send a request to signal the first stage of digits and look for a
wink (i.e. a pulse). The first stage of digits consists of
KP0ZZXXXXST/STP (national) or KP1N'XXXXXCCCST/STP (international).
-- signal addr1 --> -----addr1---->
<---"rbs/psoff"---- <-- wink ----
Send a request to signal the second stage of digits (i.e. ANI).
Signal Completion event is used to indicate when outpulsing is
complete, which supports overlap outpulsing.
-- signal addr2 --> -----addr2---->
<------"g/sc"------
Send a request to signal the third stage of digits (i.e. called)
and look for an acknowledgment wink or an off-hook request for
hold.
-- signal addr3 --> -----addr3---->
<----"rbs/psoff"--- <--- wink ----
OR
<----"bcas/ans"---- <---off-hook---
Timeouts for the receipt of the winks are specified using parameter
psto. The minimum and maximum durations of the winks are specified
using the minpsdet and maxpsdet properties.
manyfolks Informational -- Expires June 14, 2001 18
Megaco/H.248 Basic CAS Package January 2001
12.4 EAOSS Termination - IC/INC Operator Services Call indirect through
an Access Tandem (No Overlap Outpulsing):
This call flow is an optimization of the previous call flow when
overlap outpulsing is not required.
MGC MG PSTN
Start with a request to seize and report the start dialing event.
This call flow includes an embedded request to signal the first set
of address digits (i.e. KP0ZZXXXXST/STP for national or
KP1N'XXXXXCCCST/STP for international) and report an event of wink
(i.e. a pulse).
---- request -----> ----seizure--->
<------"sd"-------- <----wink------
-----addr1---->
<----"rbs/psoff"--- <-- wink ----
Send a request that includes a signal list for the second (i.e.
ANI)and third (i.e. called) stages of digits. Additionally, look for
the acknowledgment wink or off-hook hold request.
- signal addr2/3 -> -----addr2---->
-----addr3---->
<----"rbs/psoff"--- <--- wink ----
OR
<----"bcas/ans"---- <---off-hook---
Timeouts for the receipt of the winks are specified using parameter
psto. The minimum and maximum durations of the winks are specified
using the minpsdet and maxpsdet properties.
12.5 EAOSS Termination - IC/INC "National" Operator direct to the
IC/INC (Overlap Outpulsing):
MGC MG PSTN
Start with a request to seize and report the start dialing event.
Option - can use an embedded request for the first set of address
digits.
---- request -----> ----seizure--->
<---"bcas/sd"------ <----wink-----
Send a request to signal the first stage of digits (i.e. ANI).
Signal Completion event is used to indicate when outpulsing is
complete, which supports overlap outpulsing.
-- signal addr1 --> -----addr1---->
<------"g/sc"------
Send a request to signal the second stage of digits (i.e. called)
and look for the acknowledgment wink or an offhook request for hold.
-- signal addr2 --> ----seizure--->
<--"rbs/psoff"----- <--- wink ----
OR
----"bcas/ans"------ <---off-hook---
manyfolks Informational -- Expires June 14, 2001 19
Megaco/H.248 Basic CAS Package January 2001
The timeouts for the receipt of the wink is specified using
parameter psto. The minimum and maximum duration of the wink is
specified using the minpsdet and maxpsdet properties.
12.6 EAOSS Termination - IC/INC "National" Operator direct to the
IC/INC (No Overlap Outpulsing):
This call flow is an optimization of the previous call flow when
overlap outpulsing is not required.
MGC MG PSTN
Start with a request to seize and report the start
dialing event. Include an embedded request with a signal list and
look for an event of wink or offhook.
---- request -----> ----seizure--->
<---"bcas/sd"------ <----wink-----
-----addr1---->
-----addr2---->
<---"rbs/psoff"---- <--- wink ----
OR
<----"bcas/ans"---- <---off-hook---
The timeout for the receipt of the wink is specified using parameter
psto. The minimum and maximum duration of the wink is specified
using the minpsdet and maxpsdet properties.
12.7 EAOSS Origination - Telephone Operating Company serves the call:
In this call flow, the MGC is the Telephone Operating Company switch
that is providing operator services. The call originates from a PSTN
EO and terminates to the MGC for operator handling. Following
operator handling, the call completes to the packet network (not
shown).
PSTN MG MGC
Start with a request to be notified of seizure and report digits
(digit map referenced).
<---- request ----
------seize-----> ---"bcas/sz"----->
<-----wink-------
-----addr1------> -----"mfd/ce"---->
Based on the digits received (i.e. KP0ZZXXXXST/STP,
KP1N'XXXXXCCCST/STP) and the resulting translation, the MGC
determines the call should be served. Send a request to signal a
wink and report the next set of digits (i.e. ANI).
<-- request ---
manyfolks Informational -- Expires June 14, 2001 20
Megaco/H.248 Basic CAS Package January 2001
<-----wink-------
-----addr2------> -----"mfd/ce"---->
Send a request to report the next set of digits and signal an
acknowledgment wink or off-hook in place of the acknowledgment wink
(i.e. if MGC data indicates hold should be applied for this IC).
<---- request ----
-----addr2------> -----"mfd/ce"---->
<-----wink-------
OR
<---off-hook-----
Full Copyright Statement
"Copyright (C) The Internet Society (April,2000). 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 copyrights defined in the Internet Standards
process must be followed, or as required to translate it into
manyfolks Informational -- Expires June 14, 2001 21