Open Issues in SIP Service Examples Recent Changes

Open Issues • Single Line Extension – One subscription relying on forking to N

2. 10 Single Line Extension User A User B 1 B 2 B 3

2. 10 Single Line Extension (continued) User A | | | | | |

2. 16 Automatic Redial User A User B | | | INVITE F 1

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Open Issues in SIP Service Examples Recent Changes • Added SUBSCRIBE/NOTIFY using Dialog Event Package • Added Single Line Extension Flow • Added Auto Callback Flow • Changed to Require: replaces instead of Accept-Contact for Attended Transfer SIPPING 5/6/02 Meeting draft-ietf-sipping-service-examples-01. txt 1

Open Issues • Single Line Extension – One subscription relying on forking to N UAs vs. N-1 subscriptions without forking. – Requires INVITE with ‘Join’ primitive • Call Park – Park server returns extended ‘sipfrag’so that SUBSCRIBE/NOTIFY not needed. SIPPING 5/6/02 Meeting draft-ietf-sipping-service-examples-01. txt 2

Open Issues Continued • Call Pickup – SUBSCRIBE/NOTIFY flows correct? – Use of 481 to NOTIFY instead of SUBSCRIBE Expires: 0 • Auto Redial – If B is a Gateway • resource identified by Request-URI? • Contact: alan. johnston@wcom. com SIPPING 5/6/02 Meeting draft-ietf-sipping-service-examples-01. txt 3

2. 10 Single Line Extension User A User B 1 B 2 B 3 | | | INVITE F 1 | | |-------->| INVITE F 2 | | |------->| | | INVITE F 3 | |---------->| | INVITE F 4 | |-------------->| | 100 Trying F 5 | | |<--------|180 Ringing F 6| | |<-------| | 180 Ringing F 7 | | |<--------| | | 480 Not Logged In F 8| | | |<----------| | ACK F 9 | |---------->| | 180 Ringing F 10 | | 180 F 11 |<--------------| |<--------| 200 OK F 12 | | 200 OK F 13 |<--------------| |<--------| | | CANCEL 14 | | |------->| | | 200 OK F 15 | | |<-------| | | 487 F 16 | | |<-------| | | ACK F 17 | | |------->| | ACK F 18 | | |-------->| ACK F 19 | |-------------->| | Both way RTP Established | |<======================>| | | |----->| | | Both way RTP Established | | |<====>| B 3 mixes RTP | | SIPPING 5/6/02 Meeting Forking Proxy draft-ietf-sipping-service-examples-01. txt 4

2. 10 Single Line Extension (continued) User A | | | | | | | | | | | SIPPING 5/6/02 Meeting Forking Proxy User B 1 B 2 B 3 | NOTIFY F 20 | |<--------------| | NOTIFY F 21 | |------->| | NOTIFY F 22 | | |---------->| | | NOTIFY F 23 | | |-------------->| | 200 OK F 24 | |<-------| | 200 OK F 25 | |-------------->| | 200 OK F 26 | | |<----------| | | 482 Loop Detected F 27 | |<--------------| User B 2 wants to join | INVITE "Join" F 28 | | the call |<----------| | | INVITE "Join" F 29 | | |------->| | INVITE "Join" F 30 | |---------->| | | INVITE "Join" F 31 | |-------------->| | 100 Trying F 32 | | |---------->| | | 481 Dialog Does Not Exist F 33 |<-------| | ACK F 34 | |------->| | 482 Loop Detected F 35 | |<----------| | | ACK F 36 | | |---------->| | | 200 OK F 37 | |<--------------| | 200 OK F 38 | | |---------->| | | |ACK F 39 | |----->| | Both way RTP Established | |<====>| B 3 mixes RTP draft-ietf-sipping-service-examples-01. txt 5

2. 16 Automatic Redial User A User B | | | INVITE F 1 | |-------->| |486 Busy Here F 2| |<--------| User B is busy | ACK F 3 | |-------->| | SUBSCRIBE F 4 | |-------->| | 200 OK F 5 | |<--------| | NOTIFY F 6 | |<--------| | 200 OK F 7 | |-------->| | NOTIFY F 8 | User B is now available |<--------| | 200 OK F 9 | |-------->| | INVITE F 10 | |-------->| Session setup successfully | 180 Ringing F 11| |<--------| | 200 OK F 12 | |<--------| | ACK F 13 | |-------->| | Media Session | |<=======>| | | SIPPING 5/6/02 Meeting draft-ietf-sipping-service-examples-01. txt 6