[Serusers] TCP<->UDP problem

Hello, With the default configuration of SER 0.8.12, and two registered UA's using TCP as transport protocol, when I try to make a call between them, the call arrives in UDP packets ! This is the scenario: TCP TCP UA1 <---------> SIP SERVER <-----------> UA2 The UA's are registered to the SIP server using the "transport=tcp" flag in the Contact field, for example: "Contact: 12345678@80.37.88.152:13245;transport=tcp" But when UA1 calls UA2 ( using the TCP connection ), the INVITE is resent over UDP to the port specified in the Contact field, instead of using the established TCPconnection. I have tried t_relay(), forward(uri:host,uri:port) and forward_tcp(uri:host,uri:port) and all resend the INVITE over UDP. ( I don´t understand why the third case fails ¿? ) I have tried t_relay_to_tcp("80.37.88.152","13245") and forward_tcp(80.37.88.152,13245) and they work fine, but I must specify the IP:Port by hand, but I need automatically the IP:Port from the table of registered ussers. Thanks in advance for your help ! Sergio.