1. Configuration Guide
  2. SIP Signaling Services
  3. SIP SIP-I Interworking
  4. Additional ISUP IAM Generation Functions

Additional ISUP IAM Generation Functions

Additional IAM generation functions include interworking Clearmode calls, user-to-user headers, and PANI headers. These functions are specified by TS 29.163.

Clearmode Calls

While interworking a SIP INVITE message containing request for Clearmode call setup, the SBC adds the User-Service-Information parameter to the IAM message it generates. The applicable User-Service-Information subfield parameter values include:

  • Coding Standard— ITU-T standardized coding (00)
  • Information transfer capability—Unrestricted digital information (01000)
  • Transfer mode—Circuit mode (00)
  • Information transfer rate— 64 kbits/s (10000)

User to User Header Interworking

The SBC interworks user-to-user headers if the received SIP INVITE contains a user-to-user header field with the following:

  • A purpose header field parameter set to isdn-uui, (or without a purpose parameter)
  • An encoding header field parameter set to hex (or without an encoding parameter)
  • A "content" header field parameter set to "isdn-uui" (or without a "content" parameter)

If all of the above are true, the SBC maps the content of the uui-data field to the protocol discriminator and user information parameters of the user-to-user information element as it generates the IAM message.

The applicable user-to-user Information subfield parameter values include:

  • user-to-user information element identifier—0100000
  • protocol discriminator—Convert the received User-to-User header to ASCII and add the first two nibbles.
  • user information—Remove the first two nibbles (protocol discriminator) from the received user-to-user header and convert all the digits from hex to ASCII.

PANI Header Interworking

The SBC adds the location-number parameter to the IAM message if the SIP INVITE contains a P-Access-Network-Information (PANI) header that uses the format shown in the example below. 

P-Access-Network-Info:GSTN;operator-specific-GI="5522300";network-provided

The SBC follows these rules while interworking the PANI to location number:

  • Only interwork PANI headers that have an operator-specific-GI parameter.
  • Only interwork PANI headers with an operator-specific-GI parameter that contain a sequence of digits.
  • If multiple instances of PANI are present, only interwork the instance that has the access network specific component that contains a network-provided parameter.
  • If there are multiple instances that contain a network-provided parameter, use the first.
  • If none of the PANIs are network-provided, interwork the first PANI that is a GSTN type.

The SBC interworks location number subfields as follows:

  • Nature of address indicator—National (significant) number (national use) (0000011)
  • Internal Network Number indicator—Routing to internal number not allowed (1)
  • Numbering Plan indicator—ISDN (001)
  • APRI:
    • If the Privacy header is present with a value of header, use Presentation Restricted (01)
    • Otherwise, use Presentation Allowed (00)
  • Screening Indicator:
    • If the network-provided parameter is present, use Network Provided (11)
    • Otherwise, use user provided, verified and passed (01)
  • Address Signal—Value of operator-specific-GI