SIP常用消息实例参考 7、PRACK消息

7、PRACK消息
        1）头字段填写说明
        必选头域如下：
        Call-id
        Cseq
        From
        To
        Max-Forwards
        Via
        RAck
        常用可选头域：
        Content-Type
        Content-Length
        2）消息实例
        如下是PRACK消息的参考实例：

PRACK sip:192.168.2.154:5060 SIP/2.0
CSeq: 2 PRACK
Call-ID: [e-mail]
Contact: <sip:01055554444@192.168.2.46>
Content-Length: 0
From: <sip:01055554444@192.168.2.154>;tag=6c789654
To: <sip:01062237400@192.168.2.154>;tag=0012-f1939f63004dbd16
Via: SIP/2.0/UDP 192.168.2.46;branch=z9hG4bK04982ba62
User-Agent: Huawei-MC820/1.0.0
Supported: 100rel
RAck: 1 1 INVITE