Yealink T23G Phones will not provision using FQDN only ip

[deka]

We have the Enterprise version of 3cx. We have T23G phones. We can provision these phones using the local method (in lan) and the local ip address of the server.
However, if we try provisioning locally (in lan) and set the interface to the fqdn (this is a 3cx supplied fqdn) the phone sends its information over port 5000 the date and time change the 3cx pbook tab gets populated but the phone just sets at no service. (Even though this is a local provision we have made sure to enable this extension outside of LAN)

NSLookup returns correct public ip. Phones can also register using Stun.

What are we missing?

 

[leejor]

NSLookup returns correct public ip.

But is your local LAN setup to return the local IP of the server?

https://www.3cx.com/blog/docs/how-to-create-internal-fqdn/

 

[cobaltit]

You are missing the step about how networking works. What's happening is you are trying to do NAT loopback (or hairpinning) which your firewall may or may not support. Because you are using the FQDN but provisioning as local LAN your phone is trying to access 3CX over port 5000 which it will not server outside of RFC 1918 ranges. During the installation this is covered when it asks you how you want to provision local phones prefacing the requirement to control your local DNS. For this to work your local DNS needs to point the 3CX FQDN to the internal IP or you need to continue using the internal IP and not FQDN.

 

[YiannisH_3CX]

Hello @deka

Please note that what you are trying to do will not work. By choosing the FQDN as the provisioning interface you are forcing the PBX to try to provision the phone using the public IP as you do not have a local DNS entry to resolve the FQDN to the local IP of the PBX.
Since the provisioning method is local then the http (local) port is used but the provisioning requests comes to the PBX from the Public IP. The PBX will then reject the request as it only accepts HTTPS requests from public locations.