I have changed the following tm parameters in order to have an timeout INVITE equal to 20 sec (20000 ms).
# ----- tm params -----
# auto-discard branches from previous serial forking leg
modparam("tm", "failure_reply_mode", 0)
# default retransmission timeout: 20sec
modparam("tm", "fr_timer", 20000)
# default invite retransmission timeout after 1xx: 120sec
modparam("tm", "fr_inv_timer", 120000)

However, the timeout is ever 3 min (180 sec.)

In accord to tm module the timeout is defined only by "r_timer"

Then, I don't know where is the problem.

Thanks a lot for your help.

Diogenes