Outbound SIP response 480 "Temporarily Unavailable" (only certain carriers)

Hello again everybody,
I’m running FreePBX with asterisk 11.13.1.

Over the past several weeks I’ve been having periodic outbound call issues. After diagnosing for quite some time, it only appears that outbound calls sometimes fail only to certain carriers. eg. when I call a t-mobile phone number from my SIP connection sometimes the call goes through but more often then not I get the following error back from the SIP provider (and the default “all circuits are busy now” message from FreePBX).

– SIP/8511465544-out-0000024f is making progress passing it to SIP/201-0000024e
– Got SIP response 480 “Temporarily Unavailable” back from
– SIP/8511465544-out-0000024f is circuit-busy
== Everyone is busy/congested at this time (1:0/1/0)
– Executing [[email protected]:23] NoOp(“SIP/201-0000024e”, “Dial failed for some reason with DIALSTATUS = CONGESTION and HANGUPCAUSE = 19”) in new stack
– Executing [[email protected]:24] GotoIf(“SIP/201-0000024e”, “0?continue,1:s-CONGESTION,1”) in new stack
– Goto (macro-dialout-trunk,s-CONGESTION,1)

When I call other carriers, ATT, or other SIP numbers at the same carrier, I never get the 480 failures.

Anyone have an idea where I can go with this? Is it a routing issue to T-Mobile or to the carriers that are failing? Could it really be a congestion issue? I am working with my SIP carrier, but they don’t have a resolution yet either.

Thanks a lot for any help.

I have the same issue, did you solve it?