So the extension will try again with better security, it always happens, you will that the second attempt works but you are getting a 503 from the far end
The sngrep output you posted shows only communication between extension and PBX – there is nothing between PBX and trunk. But, given that you are hearing “all circuits are busy now”, I am guessing that Asterisk thinks the trunk is unavailable so it doesn’t even try.
In Reports → Asterisk Info → Peers, do you see the trunk listed under PJSIP as Avail, or under CHANSIP as OK? If not, post details.
All Sipstation new accounts require a live verbal call to verify your acct. It says this when you sign up. Did you do the live call to verify your new sipstation acct??? If not, you’ll get that all circuits are busy. It will work initially sometimes when we sign uo new clients but if the verification call doesnt take place pretty quickly you start getting the all circuits are busy…
Silly question, but you do have your trunk included in Outbound Routes, under the Route Settings tab → the Trunk Sequence for Matched Routes? I’m curious as to why FPBX would tell you that the trunk wasn’t used by any outbound routes.