Yealink T33G Phones Show “No Service” via 3CX SBC While Grandstream Phones Work

[Aldakheeloud]

Our Grandstream GXP-1625 phones are registering and operating normally, including from remote networks.


However, the Yealink T33G phones show “No Service” when connected from remote networks through our VPN/SBC environment.


The Yealink phones can work when connected within the local network, but they fail to register when used from remote locations.


Multiple Yealink T33G phones are affected, while Grandstream phones continue to operate correctly in the same environment.
Troubleshooting Already Performed

We have already performed the following:


Factory reset the Yealink T33G phones.


Deleted and re-added the phones/extensions in 3CX.


Reprovisioned the phones.


Verified the phone MAC addresses.


Verified that the Windows 3CX SBC service is running.


Verified DNS resolution of the 3CX FQDN.


Verified connectivity from the SBC server to the 3CX cloud PBX

 

[NikosT_3CX]

@Aldakheeloud as a first step ensure that the Yealink phones are on the correct firmware and provisioned
with the default template.
Check here :

https://www.3cx.com/docs/phone-firmwares/

Yealink T33G

Yealink T33G FW: Maintenance release

[td]

124.87.0.20​

[/td]​

[td]

Download​

[/td]​

 

[Aldakheeloud]

Yes we updated the phone firmware

Version

Firmware Version 124.87.0.20 Hardware Version 124.0.1.16.0.0.0

 

[Alphabetic]

Check you havent blacklisted your phones IP in 3CX?

You should really check that your network traffic from the phone is routing over the VPN too.

 

[Aldakheeloud]

There is No Blacklist our IP phone.
Same Remote Networking connected Grandstream 1625 phone work But Yealink T33G T33W show no service even configuration files sussed

 

[Alphabetic]

Has the phone pulled any config down at all?

 

[Aldakheeloud]

No ,when i changing in 3cx Admin Console,its deliery configuration But phone show no services and not register in 3cx Admin portal

 

[Alphabetic]

No ,when i changing in 3cx Admin Console,its deliery configuration But phone show no services and not register in 3cx Admin portal

if you log in to the phone, is it blank or has it pulled the config?

 

[Aldakheeloud]

yes the phone receive the configuration.
kindly check the picture.
There is Two ip phone.Greandstream 1625 and Yealink T33G both are connected same network and same configuration.
But Yealink showing no services.

 

[Alphabetic]

When you added the phone to the extension did you see a successful RPS message in event log?

You could also try adding your provisioning link into your DHCP (option 66) if the RPS is failing.

https://www.3cx.com/sip-phones/dhcp-option-66/

 

[Aldakheeloud]

yes RPS Message Delivered Successfully.

 

[Alphabetic]

Did you try pinging the FQDN from within the GUI of the phone?

 

[NikosT_3CX]

@Aldakheeloud login on the web interface of the phone, did the phone pull the config from the PBX side
and fill the appropriate details on the account ?