1. Configuration Guide
  2. SIP Signaling Services
  3. SIP SIP-I Interworking
  4. Interworking Call Flows with History-Info Information
  5. Interworking ACM or CPG with History-Info Headers

Interworking ACM or CPG with History-Info Headers

During a SIPI to SIP call, if the 180 RINGING response from SIP side contains a history-info header and the redirection mode on the egress side is set to "history-info", the SBC populates the following parameters from history-info header into the ACM/CPG message:

  • Redirection Number
  • Redirection Number Restriction
  • Call Diversion Information
  • Generic Notification Indicator

Redirection Number

Redirection Number subfield interworking includes:

  • Nature of address indicator—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).
  • Internal Network Number Indicator—The SBC always inserts the value routing to internal network number not allowed (1).
  • Numbering Plan—The SBC always inserts the value ISDN (001.)
  • Address Signal—The SBC inserts the URI of the last History-Info header containing a "cause" URI parameter.

Redirection Number Restriction

Redirection Number Restriction subfield interworking includes:

  • APRI—This interworking is dependent on the value of either the SIP privacy header or the priv-value presented in the last History-info header with a cause parameter:
    • In 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).

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

Call Diversion Information

Call Diversion Information subfield interworking includes:

  • Notification subscription options—This interworking is dependent on the value of either the SIP privacy header or the priv-value presented in the History-info:
    • If there is a value in the Privacy header or priv-value component in the History-Info header, map to that value.
    • If the Privacy header received has the value "History", "Session" or "Header" or the SBC receives a priv-value of "History" in the headers component of both the diverted-to URI and the diverting URI(s), map to presentation not allowed (001).
    • If only the History-Info header with a priv-value of history, map to presentation allowed without redirection number (011).
    • In all other cases, map to presentation allowed with redirection number (010).
  • Redirecting Reason—The SBC maps this value based on the cause parameter of the last HI entry that contains a cause parameter.
    • Cause Parameter 404—Maps to the value Unknown (0000)
    • Cause Parameter 302—Maps to the value Unconditional (0011)
    • 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—Maps to the value Deflection during alerting (0100)

Additional context information includes:

  • The diverted-to URI corresponds to the hi-targeted-to-uri of the last hi-entry containing a "cause" URI parameter.
  • The diverting URI corresponds to the hi-targeted-to-uri of the hi-entry containing a hi-index value that match the "mp" header field parameter value of the diverted-to URI. If the diverted-to URI does not contain the "mp" header field parameter, the diverting URI corresponds to the hi-targeted-to-uri of the hi-entry before the last hi-entry containing a "cause" URI parameter.
  • If there is no diverting URI (for example, an HI entry with hi-index matching "mp" param of last hi-entry with "cause" param is present) the hi-entry to use is the entry just before the last hi-entry with a cause parameter.
  • If there is only a diverted-to URI and no other URI, the SBC only refer to the diverted-to URI while populating the "Notification subscription options" parameter.

Generic Notification Indicator

In addition, the SBC sets the Generic Notification Indicator in the ACM or CPG to Call is Diverting (1111011).