SIP Statuses to Q.850 Reasons

This section explains the Oracle® Enterprise Session Border Controller’s ability to map Q.850 cause values with SIP responses, a feature used in SIP calls and calls that require IWF.

RFC 3326 defines a header that might be included in any in-dialogue request. This reason header includes cause values that are defined as either a SIP response code or ITU-T Q.850 cause values. You can configure the Oracle® Enterprise Session Border Controller to support sending and receiving RFC 3326 in SIP messages for:

Mapping H.323 Q.850 cause values to SIP responses with reason header and cause value
Mapping SIP response messages and RFC 3326 reason header and cause
Locally generated SIP response with RFC 3326 reason header and cause

As specified in RFC 3326, the Oracle® Enterprise Session Border Controller sends SIP responses to the softswitch that contain the received Q.850 cause code and the reason.

Though the Oracle® Enterprise Session Border Controller can generate RFC 3326 headers, the default behavior for this feature is disabled. Furthermore, the Oracle® Enterprise Session Border Controller can receive and pass SIP error messages (4xx, 5xx, and 6xx) that contain the SIP reason header with a Q.850 cause code and reason (as specified in RFC 3326). If the system receives an error message without the Reason header, then the Oracle® Enterprise Session Border Controller is not required to insert one.

In calls that require IWF, the Q.850 cause generated in the SIP response are the same as the cause received in the following H.225 messages: Disconnect, Progress, Release, Release Complete, Resume Reject, Status, and Suspend Reject. In addition, the Q.850 cause codes that the Oracle® Enterprise Session Border Controller receives in RFC 3326 headers are passed to the H.323 part of the call unmodified; the H.323 call leg uses this cause code for releasing the call.