Reason Header - 3Com V7122 User Manual

A
PPENDIX
This appendix describes the available mapping mechanisms of SIP Responses to Q.850
Release Causes and vice versa.
Table 97 and Table 98
Responses. To override this hard-coded mapping and flexibly map SIP Responses to ISDN
Release Causes use the parameters CauseMapISDN2SIP and CauseMapSIP2ISDN
(described in ISDN and CAS Interworking-Related
Web Server (see Release Cause
It is also possible to map the less commonly-used SIP Responses to a single default ISDN
Release Cause. Use the parameter DefaultCauseMapISDN2IP (described in
Interworking-Related Parameters) to define a default ISDN Cause that is always used except
when the following Release Causes are received: Normal Call Clearing (16), User Busy (17),
No User Responding (18) or No Answer from User (19). This mechanism is only available for
Tel to IP calls.

Reason Header

The gateway supports the Reason header according to RFC 3326. The Reason header is
used to convey information describing the disconnection cause of a call:
Sending Reason header: If a call is disconnected from the Tel side (ISDN), the Reason
header is set to the received Q.850 cause in the appropriate message (BYE / CANCEL /
final failure response) and sent to the SIP side. If the call is disconnected because of a
SIP reason, the Reason header is set to the appropriate SIP response.
Receiving Reason header: If a call is disconnected from the IP side and the SIP
message includes the Reason header, it is sent to the Tel side according to the following
logic:
If the Reason header includes a Q.850 cause, it is sent as is.
If the Reason header includes a SIP response: (1) If the message is a final response,
the response status code is translated to Q.850 format and passed to ISDN. (2) If the
message isn't a final response, it is translated to a Q.850 cause.
When the Reason header is received twice (that is, SIP Reason and Q.850), the
Q.850 takes precedence over the SIP reason and is sent to the Tel side.
454
H: R
ELEASE
describe the existing mapping of ISDN Release Causes to SIP
Mapping).
R M
EASON
Parameters), or using the Embedded
V7122 GatewayUser Guide
APPING
ISDN and CAS