I have two upstream providers we use for US termination. The dialplan sends calls out the “primary” and if that fails for specific reasons, it sends the same call out the “secondary”. This has worked well for us when we are lazy about keeping balances up, for example.
Starting a few days ago ALL calls sent to the ‘primary’ were returned as busy, though the secondary terminated them fine. We have a balance, and funny enough international calls are going through fine, just not US
calls. I opened a ticket.
The response form the carrier is that our asterisk is sending four simultaneous invites within one second, and for that reason the call is rejected.
I did a packet trace and was able to confirm this is true – only US
calls sent to this carrier cause our end to send four identical simultaneous invites. When it fails, a single invite for the same call is sent to the secondary, which is terminated without issue.
Happy to send the SIP trace if any would care to see it, but is there a reason anyone can think of that our asterisk (11.11.0) would suddenly start doing this? It may be that it has been doing it all along, and our carrier just started rejected calls that come in this way, I’m not sure.