SIP常用消息实例参考 8、INFO消息

8、INFO消息
        1）头字段填写说明
        必选头域如下：
        Call-id
        Cseq
        From
        To
        Max-Forwards
        Via
        常用可选头域：
        Content-Type
        Content-Length
        Route
        2）消息实例
        在笔者开发过程中，媒体服务器与软交换服务器之间的使用的是INFO消息交互，如下消息为软交换服务器向媒体服务器发送的INFO消息（请求开始录音），参考如下：

INFO sip:192.168.2.89:14010 SIP/2.0
Call-ID: 52f3d02182b72d37c48cea5dd013a401@192.168.2.89
From: <sip:msml@minicc:5090>;tag=013913-74fa8415d2902b1c
To: <sip:[e-mail]>;tag=-00708-b879297623d39362
CSeq: 1 INFO
Via: SIP/2.0/UDP 192.168.2.89:5090;branch=z9hG4bKf06b482d
Max-Forwards: 30
Allow: INVITE,ACK,OPTIONS,BYE,CANCEL,REGISTER,INFO,UPDATE,PRACK,REFER,SUBSCRIBE,NOTIFY,MESSAGE
Contact: <sip:192.168.2.89:5090>
Content-Type: application/msml+xml
Content-Length: 164

<?xml version="1.0" encoding="US-ASCII"?>
<msml version="1.1">
<event name="app.startingRecord" id="conf:002221c6082350d233/dialog:PRLeg708">
</event>
</msml>

       如下是媒体服务器回送的200  OK消息，消息参考如下：

SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.2.89:5090;branch=z9hG4bKf06b482d
From: <sip:msml@minicc:5090>;tag=013913-74fa8415d2902b1c
To: <sip:[e-mail]>;tag=-00708-b879297623d39362
Call-ID: 52f3d02182b72d37c48cea5dd013a401@192.168.2.89
CSeq: 1 INFO
Allow: INVITE,ACK,OPTIONS,BYE,CANCEL,REGISTER,INFO,UPDATE,PRACK,REFER,SUBSCRIBE,NOTIFY,MESSAGE
Contact: <sip:192.168.2.89:14010>
Content-Length: 0