Table Of Contents
Release 4.2 SIP-T Feature Module
For Release 4.2, Cisco BTS 10200 added the ability to carry different ISUP variants within a SIP-T message.
SIP-T is used to interconnect two Softswitches (such as the Cisco BTS 10200). In the embedded ISUP, SIP-T carries additional information that may not be available in the SIP headers. This allows for implementing ISUP- based features between two Softswitches when the originating and terminating ends of the call are in the PSTN (SS7/ISUP based).
However, using SIP-T for communication between two Cisco BTS 10200 nodes is independent of the originating and terminating protocol. The originator or terminator do not have to be ISUP—either can be any of the protocols supported by the Cisco BTS 10200.
SIP-T in Release 4.2 complies with the following specifications:
•HKTA 2202 Issue 3, Aug 2001 (for ISUP compliance)
•RFC 3372 (the SIP-T specification)
•RFC 3398 (SIP to ISUP mapping)
•RFC 3204 (MIME media types for ISUP encapsulation)
•RFC 3261 (core SIP functionality)
•RFC 2976 (SIP INFO method - for suspend and resume functionality)
The following is a list of SIP message types and the corresponding ISUP message that is encapsulated within the associated SIP message type.
•SIP INVITE - ISUP IAM
•SIP 180 response - ISUP ACM
•SIP (other 18X responses) - ISUP CPG
•SIP 200 response - ISUP ANM or CON
•SIP BYE - ISUP REL
•SIP CANCEL - ISUP REL
•SIP Error response (400 or above) - ISUP REL
•SIP INFO - ISUP SUS or RES
Release 4.2 SIP-T Requirement
When provisioning a SIP-T trunk-group, a specified ISUP variant must be associated with the trunk group. The association, in accordance with RFC 3204 (MIME media types for ISUP), is accomplished by specifying an ISUP Version (such as HONGKONG_ISUP) with an associated ISUP Base (such as itu-t92+). A fully compliant version of SIP-T that provides encode and decode capabilities for ISUP is also required.
The SIP-T Protocol
SIP-T is a protocol that utilizes SIP as a mechanism to transport ISUP messages between two IP enabled switches so that PSTN specific information are preserved when a call originates and terminates in the PSTN.
RFC 3204 defines the method by which ISUP information is carried within SIP messages for implementing SIP-T. The RFC defines a MIME media type to do this. A MIME header defines the version and base of the ISUP messages being carried within SIP. The version is analogous to an ISUP variant, while the base is similar to an ISUP protocol family.
New and Modified Tables
There are new and modified tables in the Release 4.2 SIP-T release.
The SIPT-ISUP-VER-BASE and SIPT-ISUP-VER-ALIAS tables are new to the Release 4.2 SIP-T Release.
The SIPT-ISUP-VER-BASE table is new to Release 4.2. The table contains a list of all supported SIP-T ISUP versions and their base family names. The table is used to validate the ISUP version information stored in the Softswitch trunk group profile table.
Table Containment Area
Command Line Actions
show sipt-isup-ver-base id=Q761_HONGKONG;show sipt-isup-ver-base
Primary Key Token(s)
SIPT-ISUP-VER-BASE Table Requirements
Table 2 SIPT-ISUP-VER-BASE Tokens
Token PK/FK Type Values Mandatory/ Optional
SIP-T ISUP version name.
1-32 ASCII characters
SIP-T ISUP base name.
1-32 ASCII characters
This is a new table in 4.2. This table contains aliases to the SIP-T ISUP version names defined in the SIP-T ISUP version base table.
RFC-3204 does not specify the string values to use for the version. Instead, the RFC leaves it up to the two communicating Softswitches to agree on a common value for the version string. If two Cisco BTS 10200 softswitches are communicating, then using this table is not necessary, because a pre-defined version (ID) value in the SIPT-ISUP-VERSION-BASE table can be used.
The SIPT-ISUP-VER-ALIAS table was implemented to allow Cisco BTS 10200 users to easily communicate with other Softswitches. In case the Cisco BTS 10200 is communicating with another softswitch, the table can be used to set the MIME Version string to the same value the far end softswitch is using.
SIPT-ISUP-VER-ALIAS Table Requirements
Table 4 SIPT-ISUP-VER-ALIAS Syntax Description
The SOFTSW-TG-PROFILE table was modified for the Release 4.2 SIP-T Release.
The Softswitch Trunk Group Profile (softsw-tg-profile) table holds all the information specific to a Softswitch trunk-group, such as id, protocol, indicators and echo suppression. The softsw-tg-profile record can be shared by multiple softswitch trunk groups. An ID must be created in this table before entries can be added to the Softswitch Trunk Group table.
The following modifications were made to the SOFTSW-TG-PROFILE table:
•The values of SIPT-ISUP-VER must be one of the values defined in SIPT-ISUP-VER-BASE table.
•New column, USE-SIPT-ISUP-BASE is added.
•New column, SIPT-ISUP-BASE is added. This field is populated from the SIPT-ISUP-VER-BASE table if USE-SIPT-ISUP-BASE=Y.
•CC-DIVERSION-SUPP AND DIVERSION-HEADER-SUPP Should be mutually exclusive.
•IF CC-DIVERSION-SUPP=Y; THEN DIVERSION-HEADER-SUPP=N;
•IF DIVERSION-HEADER-SUPP=Y; THEN CC-DIVERSION-SUPP=N;
•BOTH FLAGS CAN BE SET TO "N".
•IF PROTOCOL-TYPE=CMSS; THEN PRACK-FLAG MUST BE "Y";
•IF PROTOCOL-TYPE=SIP-T; THEN PRACK-FLAG MUST BE "Y";
•IF PROTOCOL-TYPE=SIP-T; then SIPT-ISUP-VER should be specified.
•SIPT-ISUP-VER must be defined in the SIPT-ISUP-VER-BASE table.
Prior to Release 4.2, ANSI was the only supported SIP-T variant. Because of this, during upgrade for all the defined SIP-T profiles, SIPT-ISUP-VER is set to ANSI_GR317, USE_SIPT_BASE to Y, and SIPT_ISUP_BASE to gr317.
SOFTSW-TG-PROFILE Table Requirements
Note Table 6 contains only the three modified SOFTSW-TG-PROFILE fields; for the complete SOFTSW-TG-PROFILE table information, refer to the Command Line Interface Reference Guide (Release 4.1).
Table 6 SOFTSW-TG-PROFILE Syntax Description
The CPM subsystem supports the new SIPT-ISUP-VER-BASE and SIPT-ISUP-VER-ALIAS tables, and the modified SOFTSW-TG-PROFILE table.
What to Provision
•SIP-T softswitch trunk group profile. SIP-T ISUP version must be defined in the SIPT-ISUP-VER-BASE table.
•Alias to predefined SIP-T ISUP versions (if needed).
When to Provision
Provision the following components before provisioning the SIP-T softswitch trunk group.
Example 1 Provisioning Exampleadd softsw-tg-profile id=ss-tg-prof; protocol-type=SIP-T; sipt-isup-ver=Q761_HONGKONG; use-sipt-ver-base=Y;add sipt-isup-ver-alias id=Q761_HONGKONG; alias=hongkong;
The DBM subsystem supports the new SIPT-ISUP-VER-ALIAS tables, and the modified SOFTSW-TG-PROFILE table.