Outbound calls vai E1 dropping out after 40-60 sec

Hello All,

I have seem many posts on this but no solution that has worked i our scenario.

We have an asterisk server with a E1 digium card. Inbound and SIP to SIP calls work perfectly. Outbound calls (SIP Phone to call placed outbound via E1 Line) though is a different story. 8 out of 10 calls just dropout.

If I watch my asterisk console I get :
chan_sip.c:701 retrans_pkt: Maximum retries exceeded on call

Any ideas/suggestions on this one ?