Outgoing Calls to External SIP server

This is what I now get when trying to make an outgoing call:

[Jan 3 20:55:32] NOTICE[11348]: chan_sip.c:2880 auto_congest: Auto-congesting SIP/SWITCH-08c91f38
[Jan 3 20:55:32] NOTICE[29274]: cdr.c:434 ast_cdr_free: CDR on channel ‘SIP/SWITCH-08c91f38’ not posted

Google is your friend. I found:

It seems that for some reason the gateway is rejecting your call. Try checking there and seeing why. If it is your carrier ask them what they see on their side. Also try with a different gateway and see what happens.