(I forward and reply this mail to the maillist).

2010/10/26 Mino Haluz mino.haluz@gmail.com:

Maybe I have not explained it very clearly, but the issue was hidden in using fix_nated_contact(). I commented it out and everything works perfect :)

Ok, that's a different problem. If you call fix_nated_contact() for a 302 then obviously Kamailio will rewrite the URI host part of the Contact header with the response public source address.