【正文】 o): Pingtel 5 5 IN IP4 Session Name (s): phonecall Connection Information (c): IN IP4 Time Description, active time (t): 0 0 Media Description, name and address (m): audio 8766 RTP/AVP 0 96 8 Media Attribute (a): rtpmap:0 pcmu/8000/1 Media Attribute (a): rtpmap:96 telephoneevent/8000/1 Media Attribute (a): rtpmap:8 pcma/8000/1該INVITE消息是用來通知SoftX3000，A用戶已經準備好等待B用戶的SIP連接。 100 TRYINGSession Initiation Protocol StatusLine: SIP/ 100 Trying Message Header CallID:call9735747654@ CSeq:2 INVITE From:sip:8882100@。tag=1c13959 To:sip:8882101@ Via:SIP/ ContentLength:0。 INVITESession Initiation Protocol RequestLine: INVITE sip:8882101@:5060 SIP/ Message Header From:sip:8882100@。tag=1c13959 To:sip:8882101@ CallID:call9735747654@ CSeq:2 INVITE ContentType:application/SDP ContentLength:199 AcceptLanguage:en Supported:sipcc,sipcc01,timer Contact:sip:8882100@ UserAgent:Pingtel/ (VxWorks) Via:SIP/:5050。branch=,SIP/（注：由于經過IFM的前轉，所以Via記錄了IFM的地址和端口） RecordRoute:sip:8882101@:5050 Expires:7200（Expires：存活時間，B用戶的響應時間必須在這個時間范圍內） Organization:Huawei,India（組織信息） Timestamp:49133Session Description Protocol Session Description, version (v): 0 Owner/Creator, Session Id (o): Pingtel 5 5 IN IP4 Session Name (s): phonecall Connection Information (c): IN IP4 Time Description, active time (t): 0 0 Media Description, name and address (m): audio 8766 RTP/AVP 0 96 8 Media Attribute (a): rtpmap:0 pcmu/8000/1 Media Attribute (a): rtpmap:96 telephoneevent/8000/1 Media Attribute (a): rtpmap:8 pcma/8000/1該消息是SoftX3000向B用戶發(fā)出請求。 180 RINGINGSession Initiation Protocol StatusLine: SIP/ 180 Ringing Message Header From:sip:8882100@。tag=1c13959 To:sip:8882101@。tag=19366 CallID:call9735747654@ CSeq:2 INVITE Via:SIP/ Contact:sip:8882101@（注意Contact是B用戶的URL地址，而非原來的A用戶的URL地址） UserAgent:Pingtel/ (VxWorks) ContentLength:0 Timestamp:49204該消息說明被叫振鈴。 200 OKSession Initiation Protocol StatusLine: SIP/ 200 OK Message Header From:sip:8882100@。tag=1c13959 To:sip:8882101@。tag=19366 CallID:call9735747654@ CSeq:2 INVITE ContentType:application/SDP ContentLength:199 Via:SIP/ RecordRoute:sip:8882101@:5050 Contact:sip:8882101@Allow:INVITE,ACK,CANCEL,BYE,REFER,OPTIONS,NOTIFY,REGISTER,SUBSCRIBE UserAgent:Pingtel/ (VxWorks) Organization:Huawei,India Timestamp:50433Session Description Protocol Session Description, version (v): 0 Owner/Creator, Session Id (o): Pingtel 5 5 IN IP4 Session Name (s): phonecall Connection Information (c): IN IP4 Time Description, active time (t): 0 0 Media Description, name and address (m): audio 8766 RTP/AVP 0 96 8 Media Attribute (a): rtpmap:0 pcmu/8000/1 Media Attribute (a): rtpmap:96 telephoneevent/8000/1 Media Attribute (a): rtpmap:8 pcma/8000/1該消息說明B用戶已經摘機，準備進入通話。 ACKSession Initiation Protocol RequestLine: ACK sip:8882101@ SIP/ Message Header From:sip:8882100@。tag=1c13959 To:sip:8882101@。tag=19366 CallID:call9735747654@ CSeq:2 ACK AcceptLanguage:en UserAgent:Pingtel/ (VxWorks) Via:SIP/:5050。branch=,SIP/ ContentLength:0 Timestamp:50440。 OPTIONSession Initiation Protocol RequestLine: OPTIONS sip:8882100@ SIP/ Message Header From:sip:8882101@。tag=19366 To:sip:8882100@。tag=1c13959 CallID:call9735747654@ CSeq:1 OPTIONS AcceptLanguage:en Supported:sipcc,sipcc01,timer UserAgent:Pingtel/ (VxWorks) Via:SIP/:5050。branch=,SIP/ ContentLength:0 Organization:Huawei,India Timestamp:50449該消息標志用戶通話階段。 BYESession Initiation Protocol RequestLine: BYE sip:8882100@ SIP/ Message Header From:sip:8882101@。tag=19366 To:sip:8882100@。tag=1c13959 CallID:call9735747654@ CSeq:2 BYE AcceptLanguage:en Supported:sipcc,sipcc01,timer UserAgent:Pingtel/ (VxWorks) Via:SIP/:5050。branch=,SIP/ ContentLength:0 Timestamp:51553該消息說明B用戶掛機后，SoftX3000向A用戶送BYE拆除它們之間的SIP連接。到此本次呼叫基本完畢。