1. Configuration Guide
  2. SIP Signaling Services
  3. SIP SIP-I Interworking
  4. Interworking Call Flows with History-Info Information
  5. Interworking IAM with Redirection Parameters

Interworking IAM with Redirection Parameters

When in receipt of History-Info information within a SIP to SIP-I INVITE call, the SBC interworking processes the following redirection parameter groups:

  • Redirecting Number
  • Redirection Information
  • Original Called Number

Redirecting Number

Redirecting Number subfield interworking 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).
  • Numbering Plan Indicator—ISDN (001)
  • APRI—This interworking is dependent on the value of either the SIP privacy header or the priv-value presented in the History-info:
    • If the value is either 'History'. 'Session' or 'Header', map to presentation restricted (01).
    • If both values are absent or have values other than those above, map to presentation allowed (00).
  • Address Signal—The SBC inserts the URI of the History-Info header whose hi-index matches the mp-parameter value of the last History-info header containing the "cause" URI parameter and the "mp" parameter.

    Furthermore, the SBC uses the hi-entry just before the last hi-entry with a cause parameter if:

    • The "mp" header field parameter is missing in the last hi-entry containing a "cause" URI parameter.
    • There is no HI entry with its hi-index matching the "mp" parameter of the last hi-entry and a "cause" parameter.

Redirection Information

Redirection Information subfield interworking includes:

  • Redirecting Indicator—The SBC interworks this field based on context and value:
    • If the Privacy header or priv-value component in the History-Info header whose hi-index matches the "mp" parameter value of the last History-info header containing the "cause" URI parameter and the "mp" parameter, the SBC uses that value.

      Furthermore, the SBC uses the hi-entry immediately before the last hi-entry with a cause parameter if no HI entry with an hi-index matching the "mp" parameter of the last hi-entry with a "cause" parameter is present.

    • If the SBC identifies this value as 'History', 'Session' or 'Header', it interworks the value to Call diverted, all redirection info presentation restricted (100).
    • If both the Privacy Header and the priv-value components are absent or both present with value other than one mentioned above, the SBC interworks the value to Call diverted (011).
  • Original Redirection Reason—Map to the value Unknown/Not available (0000)
  • Redirecting Reason—The SBC maps this value based on the last HI header entry containing a cause parameter:
    • Cause Parameter 404—Map to the value Unknown (0000)
    • Cause Parameter 302—Maps to the value Deflection immediate response (0101)
    • Cause Parameter 486—Maps to the value User Busy (0001)
    • Cause Parameter 408—Maps to the value No Reply (0010)
    • Cause Parameter 480—Maps to the value Deflection immediate response (0101)
    • Cause Parameter 503—Maps to the value Mobile Subscriber not reachable (0110)
    • Cause Parameter 487—Map to the value Deflection during alerting (0100)
  • Redirection Counter—The SBC inserts the sum of all History-Info headers in the SIP message that contain the Redirecting Reason cause parameters. This value never exceeds 5.

Original Called Number

Applicable Original Called Number subfields include:

  • 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).
  • Numbering Plan Indicator—The SBC always inserts the ISDN (Telephony) numbering plan; (Recommendation E.164)
  • APRI:
    • If the SIP Privacy value is absent or set to a value not listed below, map the APRI to presentation allowed.
    • If the SIP Privacy value is set to History, Session, or Header map to presentation restricted.

    If there are multiple history-info headers, the OCSBC selects the one with a hi-index that matches the "mp" parameter value of the first header that contains a "cause" URI parameter and an "mp" parameter. If the "mp" parameter is missing from the first history-info header that contains a "cause" URI parameter, the OCSBC uses the history-info header entry that precedes it.

    Furthermore, per the standard, the priv-value component in the history-info header can only have the values "history" or "none".

  • Address Signal—The SBC inserts the URI of the first header with a hi-index that matches the "mp" parameter value of the first header that contains a "cause" URI parameter and an "mp" parameter.

    If the "mp" header field parameter is missing in the first hi-entry containing a "cause" URI parameter, the OCSBC uses the hi-entry just before it.