Hi, Scott Yagel, you could find some clues in the file scenario.cpp of sipp project. there were some embeded scenario scripts in sipp, stored in char* default_scenario[], you can sent a register sip message by doing this: " <send retrans=\"500\">\n" " <![CDATA[\n" "\n" " REGISTER sip:CA.cym.com SIP/2.0\n" " Via: SIP/2.0/[transport] [local_ip]:[local_port];branch=[branch]\n" " From: ua1 <sip:ua1@nnl.cym:[local_port]>;tag=[pid]SIPpTag07[call_number]\n" " To: ua1 <sip:ua1@nnl.cym:[local_port]>\n" " Call-ID: [call_id]\n" " CSeq: 1 REGISTER\n" " Contact: sip:ua1@[local_ip]:[local_port]\n" " Content-Length: 0\n" " Expires: 300\n" "\n" " ]]>\n" " </send>\n" regards. Yan Lin