Interworking SIP Response to ISUP Cause Values
If a Reason header as described in IETF RFC 6432 is included in a SIP 4xx, 5xx, 6xx response, and you have enabled the sip-config, sip-response-code parameter, theOCSBC maps the Cause Value of the Reason header to the ISUP Cause Value field in the REL message, as follows:
| SIP Response | ISUP Cause Value |
|---|---|
| 400, 414, 416, 420, 421 | 111 (Protocol Error, Unspecified) |
| 403, 417, 501 | 79 (Not implemented, Unspecified) |
| 404, 485 | 1 (Unallocated number) |
| 408, 504 | 102 (Timer expiry) |
| 410 | 22 (Number Changed) |
| 422 | 31 (Normal, Unspecified) |
| 433 | 24 (Call Rejected due to feature at destination) |
| 480 | 20 (Subscriber Absent) |
| 483 | 25 (Exchange routing Error) |
| 484 | 28 (Invalid Number Format) |
| 486, 600 | 17 (User Busy) |
| 488 | 50 (Request Facility Not Supported) |
| 502 | 27 (Destination Out of order) |
| 503 | 41 (Temporary Failure) |
| 513 | 95 (Invalid Message, Unspecified) |
| 603 | 21 (Call Rejected) |
| 604 | 2 (No route specified) |
| 606 | 88 (Incompatible Destination) |
| Other | 127 Interworking Unspecified) |
For errors received from the SIP-I side, the OCSBC inserts a Reason Header into the SIP body, if it is not generated by some other process. This also requires that you have enabled the add-reason-header within the sip-config. The OCSBC inserts the SIP Reasons according to the ISUP Cause Value (cause attribute and reason) mapping from ITU-T Q.850.