IETF 76 Hiroshima DISPATCH WG

1. IETF 76 HiroshimaDISPATCH WG draft-jesske-dispatch-reason-in-responses-00 Roland Jesske: r.jesske@telekom.de Laura Liess: Laura.Liess@telekom.de draft-jesske-dispatch-reason-in-responses-00

2. Problem SIP PSTN PSTN Loss of information SIP Response Codes ISUP Cause Values ISUP Cause Values draft-jesske-dispatch-reason-in-responses-00

3. Problem ISUP Cause SIP Response 34 no circuit available 503 Service unavailable 38 network out of order 503 Service unavailable 41 temporary failure 503 Service unavailable 42 switching equipment congestion 503 Service unavailable 47 resource unavailable 503 Service unavailable 18 no user responding 408 Request Timeout SIP Response ISUP Cause 503 Service unavailable 41 Temporary failure 408 Request timeout 102 Recovery on timer expiry draft-jesske-dispatch-reason-in-responses-00

4. Reasoning The RFC 3326 says: Initially, the Reason header field defined here appears to be most useful for BYE and CANCEL requests, but it can appear in any request within a dialog, in any CANCEL request and in any response whose status code explicitly allows the presence of this header field. draft-jesske-dispatch-reason-in-responses-00

5. Requirements REQ-1: It should be possible to support PSTN-SIP-PSTN scenarios where the reason of a call release can be transferred though the SIP domain without any loss of information and no change of reason. REQ-2: It should be possible to provide correct announcements to a SIP user based on the reason for call clearing within the PSTN network or the PSTN user. The PSTN does normally not provide announcements to originating user when clearing the call. draft-jesske-dispatch-reason-in-responses-00

6. Requirements REQ-3:A UA may have the ability to display ISUP specific release causes or show a equivalent text. A inclusion of [Q.850] causes by the UE is out of scope. REQ-4:A application server providing specific PSTN like services may have the possibility to include ISUP specific release causes draft-jesske-dispatch-reason-in-responses-00

7. Used Cases A Gateway Gateway B | IAM | | | |------------------>| INVITE | | | |----------------->| IAM | | | 100 Trying |----------------->| | |<-----------------| 100 Trying | | | 603 Decline | | | | Reason Q850 #87 | REL Cause #87 | | REL Cause #87 | |<-----------------| | |<-----------------| | |<----------------- | | | | | | | | | | | | | | | Transit case draft-jesske-dispatch-reason-in-responses-00

8. Used Cases A AS Gateway B | INVITE | | | |------------------>| INVITE | | | |----------------->| IAM | | | 100 Trying |----------------->| | |<-----------------| | | | 503 Decline | | | | Reason Q850 #41 | REL Cause #41 | | | |<-----------------| | Announcement |<-----------------| | |< ================ | | | | | | | | 503 after Timeout| | | |<----------------- | | | Hybride networks (Annoncement) draft-jesske-dispatch-reason-in-responses-00

9. In which Responses The appearance of the Reason header is proposed to final responses 4xx, 5xx and 6xx and in addition for 199 Responses as defined within [I-D.ietf-sipcore-199]. In addition it was requested by the list also to allow the appearance of the Reason Header in 18x responses when included by an PSTN Gateway draft-jesske-dispatch-reason-in-responses-00

10. Proposal • Agree on the requirements, and start work • Which WG is the correct (BLISS, DISPATCH, SIPCORE? draft-jesske-dispatch-reason-in-responses-00

11. Questions / Comments draft-jesske-dispatch-reason-in-responses-00