Solved Yealink T73U Phone – Registry failure after provisioning - Phone router - provisioning impossible

[N-AGPRO]

Hello,

I'm having a problem with a Yealink T73U phone provisioned on 3CX. I'm trying to provision it as a router phone, but it's not working.

The phone seems to retrieve its configuration correctly during provisioning, but then it displays the message "Registration failed," and the extension isn't registered.

The phone is up to date with version 185.87.0.35.

I've specified its outgoing proxy by entering its own IP address.

Could you please suggest some additional checks to identify the source of the problem?

Thank you in advance for your help.

Sincerely.

 

[Charles_3CX]

Can you please update to the latest firmware version of 185.87.0.37:https://www.3cx.com/docs/phone-firmwares/

 

[vipin.rathore@thetelephon]

Since the phone is successfully downloading its configuration from the 3CX server, provisioning itself doesn't seem to be the issue. The problem appears to be happening during the SIP registration stage, which is why the phone ends up showing "Registration Failed."


One thing that caught my attention is that the phone's own IP address has been configured as the outbound proxy. I'd double-check whether that's expected in this setup, as an incorrect proxy setting can prevent the phone from registering even if provisioning completes successfully.


I'd also verify that the extension credentials are correct and make sure the extension isn't already registered on another device. Sometimes registration conflicts or authentication mismatches can cause similar symptoms.


On the networking side, it's worth checking whether the phone can properly reach the PBX for SIP/Tunnel communication. Since provisioning works, basic connectivity is there, but DNS issues, firewall rules, NAT behavior, or SIP ALG can still interfere with the registration process.


A few other things I'd check are whether the firmware version is fully supported by the installed 3CX version, whether the phone was provisioned using the correct router phone method, and whether the phone's date and time are accurate. I've also seen TLS/certificate-related issues cause registration failures in some cases.


At this point, the most useful information would probably come from the logs. If you can check the 3CX Activity Log (preferably with verbose logging enabled) and the phone's SIP logs, the SIP response code should give a much clearer indication of what's failing. A 401, 403, 404, 408, or 503 response can usually point directly to the area that needs attention.


Has anyone already checked the 3CX logs during the registration attempt? That would probably be the next step I'd take.

 

[JohnS_3CX]

Hi @N-AGPRO

I appreciate what you attempted to do with the proxy, but you shouldn't need to do that.

If it was empty then that's a sign that the built in SBC was not able to connect to 3CX, and manually adding it will not help.

1. Upgrade the phone like my colleague recommended.
2. Delete it from 3CX, then add it again fresh as a router, using the MAC on the sticker.
3. Now factory reset and once it provisions, check your Admin console, Voice & Chat, check the SBC of the phone. It must become green, and if you click it you should be able to see its Local and Public IPs populated.
4. Once they are populated, the phone will attempt to reprovision and learn its own proxy - do not do this yourself like before.
5. The phone will now activate Account 1, and proceed to register. If not, then you should try hooking it up to a different LAN, and see if it works there, as a way to test against your current LAN.

The problems we usually see is that some LANs are too restrictive and don't allow the SBC to connect, or they have MTU limitations and the phone's default MTU value needs to be adjusted by you manually if your LAN requires it.

You can also download the phone's diagnostics, dig through the folders to find 3cxsbc.log and learn whether the SBC faced issues.

 

[N-AGPRO]

Hello,

Thank you all for your replies.

By updating the firmware to the latest version, 185.87.0.37, the phone was able to register

Have a good day!