Solved Yealink T48S "No Service" issue

[SolucomPME]

Hi ! I've done a couple of searches and still not be able to fix the issue.

We have a cloud hosted 3CX Standard Licence system. We have Yealink T48S and T42 phones. Suddently, one of the phones at an employee home suddently stop working.
No changes was made to the extension, the phone or the server.
The "No Service" message along the green flashing icon appears.

The phone does shows up as connected in my 3CX admin console. If I click to reboot or reprovision the phone, it works. No logs in the 3CX log regarding this extension. I've check the box "Block Register outside LAN" and it's unticked, I've check the SIP ports in both the phone and console and they are both at 5060. I've tried to factory reset the phone, delete it from the console and add it back and reprovisionning and it's still the same issue. All our phones are provisionned through STUN.

In the router, I also tried to assign a fixed IP address to the phone and forward the ports and still not working. I also tried to disable the router firewall to see and nothing change.

Thanks in advance

 

[leejor]

Are the same type of sets used without issue at other employees homes? If so, then I'd suspect something to do with the router, and /or ISP services at this particular location. You could confirm by moving the set elsewhere to see if the issue follows.

Does this employee have other SIP services, from a provider at this location ? Or does their router have a built-in ATA? If so, then port 5060, may be used, or reserved, by those other services, at that location.

 

[Alphabetic]

Check the blacklisted IPs in your MGMT console.

 

[SolucomPME]

Finally I figured out, and don't ask me why, the 3CX extension page shows a SIP Port 5065 but when the phone get the provisionning it programs 5060 for the port. Just manually update the port through the phone menu and it starts works perfectly

 

[ChrisC_3CX]

Glad to see you got this sorted but I have to say, if the Management Console says port 5065, the IP Phone should've been provisioned with Port 5065 unless it never got provisioned.

Also, I'd recommend considering switching to using a 3CX SBC instead of STUN configuration to avoid similar issues in the future. Remember that you will have to factory reset the devices before switching to a different provisioning method. You can find our provisioning guides here: https://www.3cx.com/sip-phones/
It goes without saying that IP Phones should be running the latest supported firmware too: https://www.3cx.com/support/phone-firmwares/