3Com VCX v7111 User Manual page 273

Figure 103 SIP Call Flow
10.8.201.158
F1 10.8.201.158 ==> 10.8.201.161 INVITE
INVITE sip:6000@10.8.201.161;user=phone SIP/2.0
Via: SIP/2.0/UDP 10.8.201.158;branch=z9hG4bKacolwbzYF
From: <sip:2000@10.8.201.158>;tag=1c3535
To: <sip:6000@10.8.201.161>
Call-ID: 2123353775377NrpL-2000--6000@10.8.201.158
CSeq: 20214 INVITE
Contact: <sip:2000@10.8.201.158;user=phone>
User-Agent: 3Com-Sip-Gateway/V7111 18 PORT FXS/v.4.20.299.410
Supported: 100rel,em
Allow: REGISTER,OPTIONS,INVITE,ACK,CANCEL,BYE,NOTIFY,PRACK,REFER,INFO
Content-Type: application/sdp
Content-Length: 208
v=0
s=Phone-Call
t=0 0
o=3ComGW 87943 43401 IN IP4 10.8.201.158
c=IN IP4 10.8.201.158
m=audio 6000 RTP/AVP 8 96
a=rtpmap:8 pcma/8000
a=rtpmap:96 telephone-event/8000
a=fmtp:96 0-15
a=ptime:20
F2 10.8.201.161 ==> 10.8.201.158 180 RINGING
SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 10.8.201.158;branch=z9hG4bKacolwbzYF
From: <sip:2000@10.8.201.158>;tag=1c3535
To: <sip:6000@10.8.201.161>;tag=1c29715
Call-ID: 2123353775377NrpL-2000--6000@10.8.201.158
Server: 3Com-Sip-Gateway/V7111 18 PORT FXS/v.4.20.299.410
CSeq: 20214 INVITE
Supported: 100rel,em
Content-Length: 0
Phone 2000 answers the call, and sends 200 OK message to gateway 10.8.201.158.
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3Com VCX V7111 VoIP Gateway User Guide
INVITE F1
Ringing F2
200 OK F3
ACK F4
BYE F5
200 OK F6
10.8.201.161
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