[SR-Users] Timer

Hello we installed kamailio succesfully but we have a few problems regarding calls towards special numbers in which an INVITE is not replied with 200 OK but instead with 183 session progress sent at 1 min interval, during which the caller hears a waiting message. unless a human operator answer the call, no 200 OK is replied. if that waiting time is too long, we noticed that the call is hanged up after 3 min, 180s, that is 3 * session progress . 408 timeout is sent to the caller and cancel to the callee. we tried to adjust many timers listed in the tm module, but not seems to work we'd like to see if anybody has a clue about that ? thank you very much