Router phone not connecting to 3cx Hosted PBX

[scotru3]

Greetings,

I have 4 Yealink T44W phones I am working on setting up with a new 3cx hosted PBX installation. At my office location, I updated the 4 phones firmware. I configured the phones under appropriate users and set them to connect directly using their router features. I then setup auto provisioning. Finally, I restarted the phones and confirmed they connected to the PBX successfully and were able to make and receive calls. .Then, I relocated the phones to my client's network location and started them. The 3cx PBX shows the correct local and public IPs for the phones in their new network home under Voice & Calling. But all the phones do not connect (red square, no registration). I'm guessing this is a network configuration issue at the client site--possibly firewall. I can find lots of documentation on firewall configuration at the server/PBX side. But since the server is 3cx hosted, I assume this is all correct (and it worked fine from my office location). What network/firewall requirements are their for the network hosting the SBC or router phone? The phones are receiving IPs (via DHCP) and the computers connected through them have Internet, can browse the web and ping the 3cx server, etc... But the phones won't register. Firewall issue?

My next step tomorrow will be to try installing the SBC and see if I can connect through that. I'll post an update once I try that.

Thank you!

 

[JohnS_3CX]

Hi,

The client's network is most likely blocking the UDP traffic. The 3CX SBC built into the phone uses both TCP and UDP traffic.

The Yealink sees that UDP is not ready and even though the router is connected, the phone refuses to register its SIP account.

What version is your firmware? I need to know the specific number.

 

[scotru3]

Yealink T44W Firmware version is: 108.87.0.22

I'm working on getting access to their Microtik routing switches to explore further.

 

[scotru3]

Some additional information:

I tried installing the Windows SBC, and it connected ok.
I tried to reprovision one of the router phones to use the Windows SBC instead of using itself for routing the connection. I was unable to get the phone to auto provision. I manually downloaded the CFG file by adding the mac address to the provisioning URL and saving the file from a browser and then manually imported it using the Yealink CFG import function. The phone properly provisioned and is working through the SBC.

I'd prefer not to deploy an SBC here, but will if that's the only option. Not sure why the windows SBC is working but the phone routers are not. Also not sure why I had trouble with the auto provision or if it is related.

Also I was able to get access to the Microtik router and added firewall rules to accept all traffic to/from the 3cx hosted server, but no change.

 

[CentrexJ]

Some additional information:

I tried installing the Windows SBC, and it connected ok.
I tried to reprovision one of the router phones to use the Windows SBC instead of using itself for routing the connection. I was unable to get the phone to auto provision. I manually downloaded the CFG file by adding the mac address to the provisioning URL and saving the file from a browser and then manually imported it using the Yealink CFG import function. The phone properly provisioned and is working through the SBC.

I'd prefer not to deploy an SBC here, but will if that's the only option. Not sure why the windows SBC is working but the phone routers are not. Also not sure why I had trouble with the auto provision or if it is related.

Also I was able to get access to the Microtik router and added firewall rules to accept all traffic to/from the 3cx hosted server, but no change.

Try with a custom template and set the MTU to 1452.

network.mtu_value = 1452

We have this giant customer with almost 400 locations. Some locations had MTU issues and this solved it.