fr_inv_timer - Omid-Mohajerani/Learn-Kamailio GitHub Wiki

With fr_inv_timer we can set "invite retransmission timeout after 1xx" in Kamailio. Its a tm module parameter , so It will work if you are using tm module.

Set Ring Time (fr_inv_timer ) to 15 seconds:

modparam("tm", "fr_inv_timer", 15000)

to set the Ring time dynamically we can use t_set_fr(fr_inv_timeout [, fr_timeout])