which mentions NAT and firewalls as being potential problems. Because I can dial out with telnyx does that mean that I can eliminate NAT and firewall? I ran online port scanners with sipscanner.voicefraud.com and it found:
123.456.789.123 5060 Linksys/SPA942-6.1.5(a)
What can I do to test NAT and firewall? Is there a positive test to just say “NAT works” or “no firewall problems”?
I am not sure what you are trying to show with all this apparently unrelated information. The basic problem is that inbound does not work correct?
Not seeing anything in Asterisk CLI often means your host= or context= is wrong. Sometimes you still see something in Asterisk CLI but sometimes not. Also make sure Asterisk is listening on the SIP port the provider is sending to.
You should probably post your network information and asterisk configs instead.
So provide basic network info (Asterisk and extensions behind NAT?), your asterisk trunk configuration and sip_nat.conf.
Also try capture SIP with tcpdump from the provider IP while attempting an inbound call and post the results here.
tcpdump -nqt -s 0 -A host xx.xx.xx.xx and port 5060
If your asterisk is behind NAT I am assuming you are port forwarding 5060? Also disable SIP ALG if enabled.