请求。
4.2会话结束过程
会话的中止可以通过对INVITE 请求返回拒绝相应，对已建立的会话发送BYE 请求等方式来完成。 4.2.1 通过BYE 请求结束会话 a. UAC 的处理过程
会话中的任意一方可以通过发送BYE 请求来结束已经建立的会话。BYE 请求的生成与通用的Dialog 中请求消息的生成规则相同（参见第12 章）。BYE 请求对应一个的事务。UAC 发送BYE 请求之后即认为本次会话已经结束了。 b.UAS的处理过程
UAS 收到BYE 请求之后，需要查询匹配的会话。如果找不到则返回481 响应。如果找到对应的会话，UAS 必须结束该会话。然后对BYE 返回2XX 响应。对于正在理的请求消息，UAS 返回487 响应。
针对我们的Subcentrex的呼叫处理过成可以参见LOG培训文档，该文档将针对成功和是失败的呼叫在系统中的整个流程进行的详细的解析。 下面将演示一个具体的呼叫流程，本呼叫是NAT后面的两个设备进行呼叫，中包括信令的传输和相应的LOG信息：
218.1.121.106:59573 218.80.220.50:5060 218.1.121.106:44619 218.1.121.106:49380 | | | |
|>F1 INVITE (sdp)------------->| | | 1 PF:1 06:19:8.0469 | | | |
|<-------------- Trying 100 F2<| | | 1 PF:2 06:19:8.0487 | | | |
| |>F3 INVITE (sdp)-------------------------------------------->| 2 PF:3 06:19:8.1303 | | | |
| |>F4 INVITE (sdp)-------------------------------------------->| 2 PF:4 06:19:8.6370 | | | |
| |<--------------------------------------------- Trying 100 F5<| 2 PF:5 06:19:8.8375 | | | |
| |<-------------------------------------------- Ringing 180 F6<| 2 PF:6 06:19:12.0371 | | | |
|<------------- Ringing 180 F7<| | | 1 PF:7 06:19:12.0435 | | | |
| |<-------------------------------------------- Ringing 180 F8<| 2 PF:8 06:19:12.9273 | | | |
|>F9 REGISTER ---------------->| | | 3 PF:9 06:19:22.5059
| | | 218.1.121.106:59573 218.80.220.50:5060 218.1.121.106:44619 218.1.121.106:49380
| | | |
|>F1 INVITE (sdp)------------->| | | 1 PF:1 06:19:8.0469 | | | |
|<-------------- Trying 100 F2<| | | 1 PF:2 06:19:8.0487 | | | |
| |>F3 INVITE (sdp)-------------------------------------------->| 2 PF:3 06:19:8.1303 | | | |
| |>F4 INVITE (sdp)-------------------------------------------->| 2 PF:4 06:19:8.6370 | | | |
| |<--------------------------------------------- Trying 100 F5<| 2 PF:5 06:19:8.8375 | | | |
| |<-------------------------------------------- Ringing 180 F6<| 2 PF:6 06:19:12.0371 | | | |
|<------------- Ringing 180 F7<| | | 1 PF:7 06:19:12.0435 | | | |
| |<-------------------------------------------- Ringing 180 F8<| 2 PF:8 06:19:12.9273 | | | |
|>F9 REGISTER ---------------->| | | 3 PF:9 06:19:22.5059 | | | |
|<----------------- OK 200 F10<| | | 3 PF:10 06:19:22.5074 | | | |
|>F11 CANCEL ----------------->| | | 1 PF:11 06:19:23.9246 | | | |
|<----------------- OK 200 F12<| | | 1 PF:12 06:19:23.9299 | | | |
|<- Request Terminated 487 F13<| | | 1 PF:13 06:19:23.9302 | | | |
| |>F14 BYE --------------------------------------------------->| 4 PF:14 06:19:23.9684 | | | |
|>F15 ACK -------------------->| | | 1 PF:15 06:19:24.2412 | | | |
| |>F16 BYE --------------------------------------------------->| 4 PF:16 06:19:24.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F17<| 5 PF:17 06:19:24.5162 | | | |
| |<-----------------------------------<<< (sip incomplete) F18<| 5 PF:18 06:19:24.8175 | | | |
| |>F19 BYE --------------------------------------------------->| 4 PF:19 06:19:25.4770 | | | |
| |<--------------- REGISTER F20<| | 6 PF:20 06:19:26.8050 | | | |
| |>F21 200 OK ----------------->| | 6 PF:21 06:19:26.8066 | | | |
| |>F22 BYE --------------------------------------------------->| 4 PF:22 06:19:27.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F23<| 5 PF:23 06:19:27.8710 | | | |
| |>F24 BYE --------------------------------------------------->| 4 PF:24 06:19:31.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F25<| 5 PF:25 06:19:31.6338 | | | |
| |>F26 BYE --------------------------------------------------->| 4 PF:26 06:19:35.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F27<| 5 PF:27 06:19:35.6687 | | | |
| |>F28 BYE --------------------------------------------------->| 4 PF:28 06:19:39.4870 | | | |
| |<-----------------------------------<<< (sip incomplete) F29<| 5 PF:29 06:19:39.7516
| | | |
| |<----------------------------------------- Not Found 404 F30<| 2 PF:30 06:19:42.7775 | | | |
| |>F31 ACK --------------------------------------------------->| 2 PF:31 06:19:42.7787 | | | |
| |>F32 BYE --------------------------------------------------->| 4 PF:32 06:19:43.4970 | | | |
| |<-----------------------------------<<< (sip incomplete) F33<| 5 PF:33 06:19:44.0232 | | | |
| |<---------------------------------------------- REGISTER F34<| 7 PF:34 06:19:44.4489 | | | |
| |>F35 200 OK ------------------------------------------------>| 7 PF:35 06:19:44.4505
================================================================================ |
|<----------------- OK 200 F10<| | | 3 PF:10 06:19:22.5074 | | | |
|>F11 CANCEL ----------------->| | | 1 PF:11 06:19:23.9246 | | | |
|<----------------- OK 200 F12<| | | 1 PF:12 06:19:23.9299 | | | |
|<- Request Terminated 487 F13<| | | 1 PF:13 06:19:23.9302 | | | |
| |>F14 BYE --------------------------------------------------->| 4 PF:14 06:19:23.9684 | | | |
|>F15 ACK -------------------->| | | 1 PF:15 06:19:24.2412 | | | |
| |>F16 BYE --------------------------------------------------->| 4 PF:16 06:19:24.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F17<| 5 PF:17 06:19:24.5162 | | | |
| |<-----------------------------------<<< (sip incomplete) F18<| 5 PF:18 06:19:24.8175
| | | |
| |>F19 BYE --------------------------------------------------->| 4 PF:19 06:19:25.4770 | | | |
| |<--------------- REGISTER F20<| | 6 PF:20 06:19:26.8050 | | | |
| |>F21 200 OK ----------------->| | 6 PF:21 06:19:26.8066 | | | |
| |>F22 BYE --------------------------------------------------->| 4 PF:22 06:19:27.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F23<| 5 PF:23 06:19:27.8710 | | | |
| |>F24 BYE --------------------------------------------------->| 4 PF:24 06:19:31.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F25<| 5 PF:25 06:19:31.6338 | | | |
| |>F26 BYE --------------------------------------------------->| 4 PF:26 06:19:35.4770 | | | |
| |<-----------------------------------<<< (sip incomplete) F27<| 5 PF:27 06:19:35.6687 | | | |
| |>F28 BYE --------------------------------------------------->| 4 PF:28 06:19:39.4870 | | | |
| |<-----------------------------------<<< (sip incomplete) F29<| 5 PF:29 06:19:39.7516 | | | |
| |<----------------------------------------- Not Found 404 F30<| 2 PF:30 06:19:42.7775 | | | |
| |>F31 ACK --------------------------------------------------->| 2 PF:31 06:19:42.7787 | | | |
| |>F32 BYE --------------------------------------------------->| 4 PF:32 06:19:43.4970 | | | |
| |<-----------------------------------<<< (sip incomplete) F33<| 5 PF:33 06:19:44.0232 | | | |