Hi All, I am reading the RFC5589 related to the Call Transfer.
In Examples it is mentioned as below 6.1 <https://tools.ietf.org/html/rfc5589#section-6.1>. Successful Transfer Transferor Transferee Transfer | | Target | INVITE F1 | | dialog1 |<-------------------| | | 200 OK F2 | | dialog1 |------------------->| | | ACK | | dialog1 |<-------------------| | | INVITE (hold) | | dialog1 |------------------->| | | 200 OK | | dialog1 |<-------------------| | | ACK | | dialog1 |------------------->| | | REFER F3 (Target-Dialog:1) | dialog2 |------------------->| | | 202 Accepted | | dialog2 |<-------------------| | | NOTIFY (100 Trying) F4 | dialog2 |<-------------------| | | 200 OK | | dialog2 |------------------->| | | | INVITE F5 | dialog3 | |------------------->| | | 200 OK | dialog3 | |<-------------------| | | ACK | dialog3 | |------------------->| | NOTIFY (200 OK) F6| | dialog2 |<-------------------| | | 200 OK | | dialog2 |------------------->| | | BYE | | dialog1 |------------------->| | | 200 OK | | dialog1 |<-------------------| | | | BYE | dialog3 | |<-------------------| | | 200 OK | dialog3 | |------------------->| Figure 1: Basic Transfer Call Flow I am confused with the below Cseg Header in the INVITE message from the Transferee -> Transfer Target F5 INVITE Transferee -> Transfer Target INVITE sips:transfertar...@chicago.example.com SIP/2.0 Via: SIP/2.0/TLS 192.0.2.4;branch=z9hG4bKnas41234 Max-Forwards: 70 To: <sips:transfertar...@chicago.example.com> From: <sips:transfe...@biloxi.example.com>;tag=j3kso3iqhq Call-ID: 90422f3sd23m4g56832034 CSeq: 521 REFER Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY Supported: replaces, gruu, tdialog Contact: <sips:3ld812ad...@biloxi.example.com;gr=3413kj2ha> Content-Type: application/sdp Content-Length: ... Why in the CSeq Method value is REFER ? Since it is the new DIALOG between the Transferee -> Transfer Target As per the RFC3261 should not the CSeq Method value be INVITE ? Please help to clear my confusion. Thank you, -- With Regards Arun A. Tagare Bangalore, INDIA +91 9449 029729 _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
