Yealink T48s 66.86.0.5

[Jim Friesen]

Yealink T48s 66.86.0.5
3CX V18 Update 5

We have a client that has a few work from home workers.
The phone was working great on STUN, but the worker moved and reinstalled her phone
So new address, new internet provider. the phone now refuses to connect properly
The phone will provision.... It displays all the right info on screen.
The 3CX server confirms RPS request for Yealink T48S IP Phone delivered successfully as well as shows the phone in the phone list
The phone reboots an sits at registering....
We have confirmed it is plugged in correctly
We have tried factory resetting the phone with the same result
Added the IP address to ensure the server doesn't block the IP
Extension is allowed outside the LAN

Any thoughts?

 

[JohnS_3CX]

Hi Jim,

The worker's provider is either running SIP ALG on the modem or they are filtering SIP traffic. This basically kills STUN, so you are dead in the water. Some suggestions:

1. We have countless threads on the STUN subject, I suggest you start reading up if you still plan on using STUN but it will take up some of your valuable time to get it right.

2. Alternatively, ditch the phones and use the 3CX clients for remote workers (mobile / web / desktop)

3. Wait for update 6 coming soon - select models will have a built in SBC that will solve the exact issue you are facing and bypass such restrictions. T48S is not one of them though, read more here to get informed.

 

[Jim Friesen]

Thanks John

1: Its great to see the first person that replies, implies that i cant read or haven't done any research on the matter.
I've been part of this forum since 2017 and am fully aware of the multiple topics on STUN.

2: Company policy does not allow the clients only physical phone.

3: I've previously read all about the built in SCB coming in some future update.... that doesn't help me today.

 

[JohnS_3CX]

Hi Jim,

1. No offence intended, I did not want to assume your level of knowledge. I always tend to suggest people read up because we have come across various (sometimes very detailed) scenarios on the subject and there might be a bit of information in a couple of threads out there that could help on your specific case.

2. Understood, that's perfectly fine.

3. For today, the best I can suggest is to try and (sorry for this) gain access to the worker's modem, and do the best you can to disable SIP ALG, and then port forward the SIP and RTP range. There are no guarantees I'm afraid, given the myriad of modems out there which all have their own implementation of how to NAT and ALG. If you want to get deeper, you could run a pcap on the phone UI and see what the phone gets when it tries to register.

If they block SIP entirely, you might be stuck and will have to consider other methods.
Perhaps run our SBC on their Windows PC?

 

[Jim Friesen]

Hi Jim,

1. No offence intended, I did not want to assume your level of knowledge. I always tend to suggest people read up because we have come across various (sometimes very detailed) scenarios on the subject and there might be a bit of information in a couple of threads out there that could help on your specific case.

2. Understood, that's perfectly fine.

3. For today, the best I can suggest is to try and (sorry for this) gain access to the worker's modem, and do the best you can to disable SIP ALG, and then port forward the SIP and RTP range. There are no guarantees I'm afraid, given the myriad of modems out there which all have their own implementation of how to NAT and ALG. If you want to get deeper, you could run a pcap on the phone UI and see what the phone gets when it tries to register.

If they block SIP entirely, you might be stuck and will have to consider other methods.
Perhaps run our SBC on their Windows PC?

Thankyou
We have tried but cannot access those settings in the user login of the router so we are reaching out to the internet provider in hopes they can turn off any type of SIP blocking and or SIP ALG
In the mean time i will run a PCAP and see if it gives any light on the problem
It also didn't occur to me running SBC on their laptop, that might be a great option if she has enough resources available.