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

Interworking Call Flows with History-Info Information

For interwork in which there are devices that support SIPI/SIP-T, the SBC supports SIP History-Info interworking. This feature enables such devices to function properly in instances that require SIP-T/SIP-I style ISUP message encapsulation in ISUP requests, and to receive any call forwarding information in the message according to ISUP standards.

For interwork in which there are device that support SIPI/SIP-T, the OCSBC support History-Info interworking

In the scenarios of call forwarding, when incoming INVITE, 180 or 200 OK messages contain "History-Info" header, the SBC encodes IAM, ACM (or CPG) and ANM (or CON) parameters described in the sections below.

Important configuration reminders with respect to the applicable sip-profiles include:

  • If the ingress is set to ISUP and the EGRESS is set to SIP, the SBC removes ISUP content while forwarding request and add ISUP content using history-info headers while sending back response
  • If the ingress is set to SIP and the EGRESS is set to ISUP, the SBC adds ISUP content using history-info headers while forwarding request and remove ISUP content while sending back response

Important operational behaviors include:

  • The SBC only interworks History-Info headers in SIP or SIPS format, per RFC 4458. An example of this format, using SIPS, is below.
    History-Info: <sips:UserA@ims.example.com;user=phone;cause=302?Privacy=history>;index=1.1;mp=1.1
  • If a History-Info header contains comma separated values, the SBC considers the first value as top most and the last one is the bottom most.