On Tue, Aug 16, 2016 at 04:14:15PM +0200, Olle E. Johansson wrote: > > I'm seeing a different behavior of t_set_fr depending on transports. > Which is correct. UDP is connectionless and thus SIP has timers for > retransmits and fails when there’s no response. With connection-oriented > protocols, the failure happens when the connection fails, which in many > cases is much faster and not based on any retransmission timers. > > In fact - failures in TCP is quite operating system dependent if the URI > results in an IP address. There are some interesting papers on this topic > which for SIP lead to the development of solutions like SIP outbound.
I understand what you are saying, but I'm interpreting the documentation for the fr_inv_timer/t_set_fr totally different (on an other OSI layer (7 instead of 4)) http://kamailio.org/docs/modules/4.3.x/modules/tm.html#tm.p.fr_timer >4.2. fr_inv_timer (integer) > >Timer which hits if no final reply for an INVITE arrives after a >provisional message was received (in milliseconds). > >Note: This timer can be restarted when a provisional response is >received. For more details see restart_fr_on_each_reply. > >Default value is 120000 ms (120 seconds). > >See also: t_set_fr(), max_inv_lifetime. The timer doesn't care about retransmits for the messages itself, it cares about the max time between initial provisional response for the INVITE and a final response (2/4/5/6xx). This reads as to be independent of the transport layer. Either way this isn't a big problem for me since I only used TCP to get around a packetcapture problem with fragmented packets. But surely there should be a way to to redirect/forward a call to another destination at an arbitrary time regardless of transport protocol. _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users