[fpc-pascal] Help Reading SIP Messages.

lloyd thomas lloydie.t at googlemail.com
Tue Jan 5 14:08:34 CET 2010

Please forgive my ignorance regarding the project I am about to embark on.
Need some advice on Lnet and capturing SIP RTP data to file. In the first
instance I just need to work with the sip messages. I believe the SIP
messages are similar to HTTP. I am using wireshark to understand how the SIP
messages are processed, but I am not sure how to capture and read each frame
(wireshark speak) using Lnet.


For instance the following is from frame 12 (935 bytes)
INVITE sip:1002 at <sip%3A1002 at> SIP/2.0
From:"Lloyd" <sip:1000 at <sip%3A1000 at>
To:<sip:1002 at <sip%3A1002 at>>
Contact:"Lloyd" <sip:1000 at;transport=UDP>
Call-ID:83570000-4ce59f27 at<Call-ID%3A83570000-4ce59f27 at>
Subject:sip phone call
CSeq:2112045024 INVITE
User-Agent:Mitel-5212-SIP-Phone 08000F24BEE5
Session-Expires: 1800
Min-SE: 90

o=1000 1262650963 1262650962 IN IP4
s=SIP Call
c=IN IP4
t=0 0
m=audio 20036 RTP/AVP 0 8 18 96
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=rtpmap:96 telephone-event/8000

I get a response from the sip server on frame 13 (371 bytes)
SIP/2.0 100 Trying
Via: SIP/2.0/UDP;rport=5060;branch=z9hG4bK83570061
From: "Lloyd" <sip:1000 at <sip%3A1000 at>
To: <sip:1002 at <sip%3A1002 at>>
Call-ID: 83570000-4ce59f27 at
CSeq: 2112045024 INVITE
User-Agent: FreeSWITCH-mod_sofia/1.0.trunk-15355M
Content-Length: 0
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