Hello... Regarding making SIP hop for you in your first session! As any programmer knows, getting the first "Hello world" back from a new computer language is the hardest hurdle. After that, you look back after a few thousand pages of code and say... "easy". Doing this all a little at a time will teach you it in a deep sense. If you just want to make a call and not know how it works: Bum a quarter and find a payphone instead! Anyway, here is a canned example of a TCP hand coded SIP session that works as of this morning. SIP tends to just hangup without an response code unless the session is reasonably well formed. The below works. Thanks Henning S. for inventing SIP! and making the client exist on columbia.edu as below. This is via TCP using a telnet client under linux. I telneted to the linux box from home using a telnet client under Windows. Anyway, it couldn't make the UDP open, but that is "hello world plus" so once you have the response code to parse... the low level is working, obviously. The below is a "telephone call" to Columbia university via internet hand routed without software. This is a good way to learn it in depth. The best actually. The top block is what I hand entered, and the bottom is the (HA!) "phone switch". Stimus and response, hand entered. Somewhere I read some Telnet clients inserts extra [CR LF[ sequences which goofs up the [CR LF] detection. SO enter it carefully by hand once and you will be far ahead. If you get a "200 Bad thing" etc you know your firewalls and what have you is not in the way. Regards, Dan K TELNET telnet> open sip.columbia.edu 5060 Trying 128.59.39.127... Connected to ren.cc.columbia.edu. Escape character is '^]'. INVITE sip:a@xxxxxxxxxx SIP/2.0 Via: SIP/2.0/UDP 169.130.4.4 FROM: <sip:test@xxxxxxxxxx> TO: <sip:test2@xxxxxxxxxx> call-id: 123456@Dbk@test.com content-length: 0 SIP/2.0 400 Transaction tupel incomplete (9/SL) Via: SIP/2.0/UDP 169.130.4.4;received=204.101.26.60 FROM: <sip:test@xxxxxxxxxx> TO: <sip:test2@xxxxxxxxxx>;tag=b27e1a1d33761e85846fc98f5f3a7e58.16fb call-id: 123456@Dbk@test.com Server: Sip EXpress router (0.8.12 (i386/linux)) Content-Length: 0 Warning: 392 128.59.39.127:5060 "Noisy feedback tells: pid=13647 req_src_ip=204.101.26.60 req_src_port=4829 in_uri=sip:a@xxxxxxxxxx out_uri=sip:a@xxxxxxxxxx vi a_cnt==1" Example: 4769498 "First SIP call" Regards, Dan Kolis