[Serusers] HELP: re-INVITE Sometimes Not Processed Properly

Hi All. I really need some help here. Attached is a call log between my ser-0.9.1 sip proxy and a third party Sonus PSTN gateway. The call was originated on a SIP phone so the Sonus gateway sends re-INVITE messages during the call. The problem is that the re-INIVITE is not properly processed and therefore the PSTN gateway sends a BYE message (not shown). I'm using Juha's LCR module because we have multiple PSTN gateways. Anyhow, it seems like this is happening: INVITE sent to PSTN gateway PSTN GW sends 180 Ringing PSTN GW sends 200 OK, which is sent to the SIP UA SIP UA replied with ACK, which is sent to the PSTN GW Time Elapses PSTN GW sends re-INVITE, which is sent to the SIP UA SIP UA replies with 200 OK, which is sent to the PSTN GW PSTN GW sends another re-INVITE PSTN GW sends an ACK, which is sent to the SIP UA re-INVITE (received immediated before the ACK) is sent to the SIP UA And the call falls apart from here. It's like some sort of timing issue where another INIVITE is recieved before the ACK. My timers in ser.cfg are as follows: modparam("tm", "fr_timer", 22) modparam("tm", "fr_inv_timer", 27) modparam("tm", "wt_timer", 5) modparam("tm", "fr_inv_timer_avp", "inv_timeout") Can anyone give a pointer please? I'm 100% lost on this one. Regards, Paul