IAM Interworking Support
When configured for IWF, the SBC supports SIP-SIPI IWF in both directions. For SIPI to SIP interworking, the SBC constructs the SIP headers based on the SIPI information, then removes the entire IAM block. For the SIP to SIPI direction, the SBC interworks IAM parameters as described here and inserts the block.
Assuming you have configured a sip-isup-profile and a sip-profile on the applicable interfaces, the SBC performs this interworking regardless of the sipi-behavior configuration. It is recommended that you do not configure IAM interworking using HMR or session translation.
The SBC supports the insertion of the IAM message based on the configured redirection parameter in the applicable sip-profile and the version field in the applicable sip-isup-profile. The SBC inserts the body after any application/sdp body parts, if that body is already in the INVITE.
When configured for native IWF, the SBC interworks the following IAM parameters:
- Called Party Number
- Nature of connection Indicator
- Forward Call Indicators
- Calling Party Category
- Transmission Medium Requirement
- Calling Party Number Parameter
- Generic Number
Called Party Number
For Called Party Number, mapping includes:
-
Nature of address—The SBC inserts the following values into the IAM, based on the conditions described:
- National, if there is no + in the number (encoded to 0000011).
- International, if there is a + in the number (encoded to 0000100).
- Special Number, if there is a phone-context parameter in the request-uri user part, and that number does not start with a + or a 0 (encoded to 1110011).
- Internal Network Number Indicator, with a sole value of 1, indicates routing to an internal network number is not allowed.
- Numbering Plan, which is always ISDN.
Nature of connection Indicator
For Nature of connection Indicator,
- No Satellite Circuit—If the SIP messaging includes the Satellite Indicator
- No continuity Check—If the SIP messaging includes the Continuity Check indication
- Outgoing Echo Device Included—If the SIP messaging includes the Echo control device indicator
Forward Call Indicators
For Forward Call Indicators, the SBC inserts the following values into the IAM, based on the SIP indicators listed:
- No end-to-end method available—If the SIP messaging includes the End-to-end method indicator
- Interworking encountered —If the SIP messaging includes the Interworking indicator
- No end-to-end information available—If the SIP messaging includes the End-to-end information indicator
- ISDN user part/BICC not used all the way—If the SIP messaging includes the ISDN user part/BICC indicator
- ISDN user part/BICC not required all the way—If the SIP messaging includes the ISDN user part/BICC preference indicator
- Non-ISDN Access—If the SIP messaging includes the ISDN access indicator
- No Indication—If the SIP messaging includes the SCCP method indicator
- Number not translated—If the SIP messaging includes the Ported number translation indicator
- No QoR routing attempt in progress—If the SIP messaging includes the query on release attempt indicator
Calling Party Category
The SBC always inserts the value Ordinary calling subscriber for Calling Party Category, encoded as 000010101, regardless of the SIP signaling.
Transmission Medium Requirement
For Transmission Medium Requirement (TMR), the SBC inserts the TMR, coding it based on the content of the incoming SDP:
- 64 kbit/s unrestricted—If the Clearmode codec is present in incoming SDP (encoded to 00000010).
- 3.1 kHz audio—For all other cases (encoded to 00000011).
Calling Party Number
The IAM Calling Party Number equates to a combination of the ISUP Address of Signal and Address Presentation Restricted Indicator (APRI). The SBC maps this data based on the SIP PAI, FROM URI, and Privacy Value. as shown in the following table.
| P-Asserted-Identity | From URI | Privacy Value | Address Of Signal | APRI |
|---|---|---|---|---|
| Not Present | Non E.164 | Any | Omit | Omit |
| Not Present | Including E.164 | Absent or with value “none” | Empty | Unavailable |
| Not Present | Including E.164 | Value different than “none” | Empty | Unavailable |
| Present | Any | Absent or with value “none” | P-Asserted-Identity userpart | Presentation allowed |
| Present | Any | Value different than “none” | P-Asserted-Identity userpart | Presentation restricted |
The SIP P-Asserted-Identity and Privacy headers may or may not be present in the INVITE. In addition the SIP From header is always be present, but it may contain an anonymous URI, often formatted as anonymous@anonymous.invalid.
In addition, the SBC always fills in other parameters as follows:
-
Nature of address:
- National, if there is no + in the number (encoded to 0000011).
- International, if there is a + in the number (encoded to 0000100).
- Numbering Plan—Always ISDN.
- Screening Info—Always Network Provided.
- Number Incomplete Indicator— Always set as Complete.
Generic Number
The Generic Number parameter is mapped the similarly to the Calling Party Number. The table below shows this mapping.
| P-Asserted-Identity | From URI | Privacy Value | Address Of Signal | APRI |
|---|---|---|---|---|
| Not Present | Including E.164 | Any | Omit | Omit |
| Any | Non E.164 | Any | Omit | Omit |
| Present | Including E.164 | Absent or with value “none” | From userpart | Presentation allowed |
| Present | Including E.164 | Value different than “none” | From userpart | Presentation restricted |
The SIP P-Asserted-Identity and Privacy headers may or may not be present in the INVITE. In addition the SIP From header is always be present, but it may contain an anonymous URI, often formatted as anonymous@anonymous.invalid.
In addition, the SBC always maps the Generic Number, Number Qualifier Indicators to Additional Calling Party number parameters as follows:
-
Nature of address:
- National, if there is no + in the number (encoded to 0000011).
- International, if there is a + in the number (encoded to 0000100).
- Numbering Plan—Always ISDN.
- Screening Info—Always user provided and not verified.
- Number Incomplete Indicator— Always set as Complete.