Thanks Klaus, I have tried to resolve this problem a lot of time. I think I forcing SER to relay to tcp and at a moment it seems that my test goes wrong : I'm testing only the URI to evaluate if transport=tcp is present. Perhaps there is another way to be sure that SER must relay to tcp. Which header to test to be sure that a transport=tcp is required by the other side? I remember A message I have seen about that but after may hours searching in the user list I didn't find it... I trusted in SER t_relay to simply automatically resolve the protocol to be used... but No way... Any idea and help would be welcome. Thx Christian -----Original Message----- From: Klaus Darilion [mailto:klaus.mailinglists@pernau.at] Sent: quarta-feira, 1 de março de 2006 08:06 To: cthomas(a)canalwest.com Cc: serusers(a)lists.iptel.org Subject: Re: [Serusers] TCP connect and other related stuff problems Ser tries to connect to a remote party (the gateway?) using TCP but fails to connect because the remote party does not answer. use tcpdump to debug the TCP connection setup. Dumping some ngrep traces would also help. regards klaus Christian Thomas wrote: