503 Transport failure: no transport left to try; warning: No other DNS entries to try (7,110); internal

[sergio.londono]

Hello team,

Version: 16.0.5.619
Debian
DNS: Primary 4.4.2.2, backup 8.8.8.8

We are getting intermittent outbound calls error:
Event log:
503 Transport failure: no transports left to try; warning: No other DNS entries to try (7,110); internal
Device used to execute outbound calls: Webclient, 3CX app android

The call doesn't arrive to the sip trunkView attachment 17566, so, it looks like the 3CX is dropping the call for internal reason.

I don't know the reason, maybe do you have any idea that can help me to solve the issue?

 

[cobaltit]

You might want to provide some more information:

https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

No idea if this happened since day 1, just started happening, etc. No mention of the trunk provider either. Is it a supported trunk?

I'd start by dropping 4.4.2.2 and making 8.8.8.8 your primary DNS.

 

[sergio.londono]

1. Some information about you system that is almost always useful is the following:

• 3CX Version, e.g. Standard Annual 16.0.5.619
• Server OS, Operating System : Debian GNU/Linux 9.12
• Is the 3CX Server Hosted and where: Hosted over our cloud KVM Promox Hypervisor
• IP Phone Make/Model/Firmware:The calls are generated by Webclient and 3cx app android
• Provisioning Method: Local / VPN / STUN / SBC: Internet using tunnel 3CX
• Trunk Provider: Convergia
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: NO

We already changed the DNS to 8.8.8.8 and 8.8.4.4.

No errors since changed DNS, I will continue today with the troubleshooting trying to capture a *.pcap that show a live call with error.