We use a presence module with the enabled option "timeout_rm_subs". And we face issues that subscriptions remove too early. We expect that it will be removed after the fr_timer, but it is removed after 1 second. 

We I can see in log (i'm add additional logs):

when we send NOTIFY:

tm [timer.c:491]: retr_buf_handler(): timer retr_buf_handler @1436309038 (timer_ln 0x7f4708f45bd0 -> rbuf 0x7f4708f45bb0 -> [0x7f4708f458a0 <-> 11592:145228
527])

tm [timer.c:492]: retr_buf_handler(): fr_expire 1436309054  T1 4000  T2 4000 fr_timeout 80

tm [timer.c:536]: retr_buf_handler(): new interval 4000 ms / 64 ticks (max 4000 ms)

when timer expire:

tm [timer.c:491]: retr_buf_handler(): timer retr_buf_handler @1436309054 (timer_ln 0x7f4708f45bd0 -> rbuf 0x7f4708f45bb0 -> [0x7f4708f458a0 <-> 11592:145228
527])

tm [timer.c:492]: retr_buf_handler(): fr_expire 1436309054  T1 4000  T2 4000 fr_timeout 80

tm [timer.c:367]: final_response_handler(): transaction [0x7f4708f458a0 <-> 11592:145228527] scheduled for deletion

tm [timer.c:424]: final_response_handler(): stop retr. and send CANCEL (0x7f4708f458a0)

and then subscription remove. 

As we can see the fr_expire variable was set to ticks+16 ( 1 second). And another strange thing that T1 and T2 timers are the same.

So the question is if this behaviour is correct, how can we configure the presence module fr_timer as an expiration value for the answer to notify? And can we use it without retransmissions?