Hello, I am running into a problem where I am experiencing duplicated INVITE's being originated from Kamailio proxy. U 2011/12/13 23:58:17.543802 KAMAILIO:5060 -> PSTN:5060 INVITE sip:URI@PSTN SIP/2.0. U 2011/12/13 23:58:17.543840 KAMAILIO:5060 -> PSTN:5060 INVITE sip:URI@PSTN SIP/2.0. As you can see that the timestamp between the two invites is literally a fraction of seconds. There is no failure condition that is causing this with append_branch There is no retransmission timer issue that is causing this (using default timing): modparam("tm", "retr_timer1", 500) modparam("tm", "retr_timer2", 4000) Any thoughts / ideas - as this is causing a race condition in which there is a 200 OK that is being sent back from upstream -- and we are then CANCELING the 2nd INVITE which is essentially causing on overall problem with the call. Thanks for all help / thoughts / input in advance, thanks! Sincerely, Brandon Armstead