[Serusers] 503 Service Unavailable processing

Friends, Can anyone point me in the right direction with respect to processing 503 (service unavailable) replies?! I did some testing and here is what I have found so far: 1. I expected the 503 to be received in failure_route but, contrary to my expection, I am catching it in onreply_route 2. I tried to relay the call within onreply_route to an IVR but the t_relay fails giving the message: DEBUG: w_t_relay entered! 12(20326) ERROR: w_t_relay_to: unsupported mode: 2 ERROR: w_t_relay_to: unsupported mode: 2 3. I tried processing the 503 upon receipt of next message at the top of routing configuration but didn't work: a) I set an avpop in onreply_route upon receipt of 503 and checking it at the top of my configuration in the next round but the avp_check returns false b) I set a flag in onreply_route upon receipt of 503 and checking it at the top of my configuration in the next round but isflagset returns false c) I set a gflag in onreply_route upon receipt of 503 and checking it at the top of my configuration in the next round but isgflag_set returns false Any suggestions would be very much appreciated. Thanks a bunch ramin