[Kamailio-Users] Openser configured as outbound proxy - retransmissions issue.

Hello all, I am working on configuring openser as a outbound proxy. User agents register to service provider through openser outbound proxy. I am experiencing issues with retransmissions. Case 1. UA sends an INVITE to Proxy and proxy is down. Openser  sends 100 Trying to UA and retransmits INVITE messages to proxy. After 8 retry attempts sends 408 Request time out to handset. All as expected. Case 2: Openser received INVITE for UA from proxy. UA is down. Openser sent 100 Trying to proxy and routes reqest to UA. No response from UA and ** Openser did not send any retransmissions of INVITE to UA**. After a while CANCLE arrived at openser and cleared transaction. why openser does retransmissions in Case 1 and why not in case 2? Can openser proxy be operated in stateful outbound proxy to take care of retransmissions? I am using default openser config file. Is there any thing I am doing wrong? Any help is greatly appreciated. Thanks Sid