Solved Phone wont register behind new SBC

[NicoC]

Hi All,

We have taken over support for a large client that has over 50 sites all connecting with their own SBC back to a central server.
Everything appears to be working well except for one site that is experiencing audio issues
I have had a look and it is possible that they are reaching the BLF limit for a single SBC

I have fired up a new linux SBC from the iso and connected it back to the 3CX server which is showing both the WAN IP address and the internal IP address 192.168.1.4. The status of the SBC is green and from what I can see the SBC is happy with its connection back to the server.

I am trying to get some of the phones across onto to new SBC, so have gone into the extension and changed the SBC address from 192.168.1.3 to 192.168.1.4. I have then gone to the web interface of the phone and done a factory reset. The phone has provisioned, rebooted a couple of times and configured itself correctly with the proxy address of 192.168.1.4, but the registration fails.

I have then changed the SBC address in the extension back to .3 and factory reset the phone and it has reconfigured itself and registered. What should I be checking next?

 

[Alphabetic]

It could well be that the port(s) 443 or 5001 are being blocked out at the site firewall or limited to .3

Run a trace on the 3CX and see if the registrations are hitting you when on .4 vs .3

 

[ChrisC_3CX]

What @kieferschild might be the case but if you've already factory reset the phones and reprovisioned them successfully then the HTTPS port should be accessible to the IP Phones. Are you 100% sure the IP Phones provisioned? I mean you did mention seeing the correct proxy address which should be proof enough but can you also check the SIP account settings on the IP Phones and confirm they are the correct extension settings? All this provided that you did perform a factory reset before provisioning.

 

[NicoC]

I have double-checked the site and they have a little ubiqiti router but it doesn't have any rules in place preventing access to ports.

I was thinking the same thing as you Chris, if it was a port issue my assumption would be that the SBC would not connect at all back to the server (Which it has and shows a valid up time)

As for the phone, I am positive that it is communicating through the SBC to get provisioning and extension information from the server. To confirm, I performed the following test.

1. The extension was setup as Boardroom and registered when using SBC .3
2. I went into the extension and changed the first name to Boardroom test and changed the SBC to .4
3. I went to the web interface of the phone, settings, upgrade, factory reset
4. The phone comes up with the default Yealink web interface and default UN/PW and proceeds to reboot two more times
5. The web interface of the phone now uses the same password as listed in the web interface field in the extension
6. Checking the account tab shows the Boardroom Test in the first name and has the proxy address listed as .4, but fails to register.
7. I have also gone into the security tab and turned off trusted certificates and rebooted the phone, but it still fails to register

Repeating the steps in reverse to use .3 results in the phone registering which also eliminates that the WAN IP address of the site has been blacklisted preventing registration

 

[SteveITS]

Do they have up to date firmware? You tagged the post 'Yealink' but didn't specify a model or firmware.

There was an issue back in late September when a Let's Encrypt root cert expired. Phones that didn't have the cert wouldn't register properly, as I recall. There was a 3CX hotfix released back in early October as I recall.

 

[NicoC]

Do they have up to date firmware? You tagged the post 'Yealink' but didn't specify a model or firmware.

There was an issue back in late September when a Let's Encrypt root cert expired. Phones that didn't have the cert wouldn't register properly, as I recall. There was a 3CX hotfix released back in early October as I recall.

Hi yes sorry i forgot to mention the model.

It is a yealink T41S. The firmware on the phone is 66.86.0.5 which is the latest version according to the following page https://www.3cx.com/support/phone-firmwares/

 

[NicoC]

I should also mention that the server is v18 build 314 and the SBC is version 18.1.34

 

[ChrisC_3CX]

3. I went to the web interface of the phone, settings, upgrade, factory reset
4. The phone comes up with the default Yealink web interface and default UN/PW and proceeds to reboot two more times

Here I'm not sure I completely understand what is happening. Can you provide the exact steps you follow to get it provisioned? I'm asking because, after you factory reset, what I would expect you do is then:

• Access the Management Console.
• Go to the Phones section.
• Select the IP Phone and hit assign.
• The IP Phone should then automatically provision with the settings of the extension selected.

Can you confirm if these are the exact steps or if you're doing something else?

I suspect there exists a communication issue between the IP Phone and the second SBC. Is there some sort of network configuration on this site, you can think of, that might indeed cause communication issues between the IP Phones and the second SBC?

If this is the case it would explain why the SBC is up, the IP Phone provisions, but still not registers.

 

[NicoC]

The phone is already assigned to the extension.
From my understanding, the SBC will function similarly to option 66 in that it essentially provides the provisioning URL to any device behind it.

When the device communicates over that provisioning URL, 3CX will check to see if that MAC address matches an existing phone.

In this case that mac address is on extension 0276, it then grabs all the details about that extension and configures the phone with those extensions details including things like changing the default username and password on the phone to whatever is specified in the extension as well. Finally, the phone reboots a couple of times while it finishes configuring itself and will then try and register back to the PBX over the SBCs connection with the extension details it obtained during the provisioning step.

If this were a brand new phone that had never been used anywhere then yes the process would be that you would have to assign the phone to an extension, but after it is assigned you would not need to re-assign the phone every time it was factory reset.




As for the exact steps for reprovisioning the phone. The phone is already assigned to an extension as it has been connecting via the sbc .3 in the past.

When you go into the yealink web interface (using the"Phone web page password" specified in 3cx), you go into the setup tab, click on upgrade on the left-hand side and then select reset to factory. The phone will proceed to reboot and wipe all settings. At this point when the phone comes back up you can log and you can log into the web interface using the default yealink un/PW combination, this indicates that the phone has been completely restored to factory.

After about 30-45 seconds the phone will have checked in with the 3CX server and grabbed a copy of its provisioning details and begins rebooting (I believe it reboots two more times). Once the phones web interface is responding again the default credentials will no longer work and you will need to use the password that is specified on the extension in 3CX.

Finally, logging into the phone the account section will contain the details of the account that has the matching MAC address details stored in 3CX

 

[Alphabetic]

The phone will send out a multicast that the sbc will pick up and report back to the pbx. From the pbx you have to push the config to the phone by using either assign ext or add ext. you have to do this if you are not using option 66 as the pbx won’t automatically dish it out and the phone isn’t asking the pbx for its config because it doesn’t know the provisioning url

 

[NicoC]

The phone will send out a multicast that the sbc will pick up and report back to the pbx. From the pbx you have to push the config to the phone by using either assign ext or add ext. you have to do this if you are not using option 66 as the pbx won’t automatically dish it out and the phone isn’t asking the pbx for its config because it doesn’t know the provisioning url

I understand what you are saying but am pretty sure that if you have the details of a phone already assigned to an extension, it will result in that extensions details being provisioned to the phone. i have confirmed this through the following step

1. Connect the new phone
2. Assign to an extension and let phone provision and register
3 Factory reset the phone and at the same time add the word test into the extensions First name
4. Phone resets, automatically checks in with server and provisions itself
5. Phone is provisioned with the word test in the first name

 

[Alphabetic]

If you’re resetting the phone immediately after sending the prov link from the 3CX then I can only assume it’s still being served the link. Give it 10 minutes after provisioning and factory reset your phone again to see what happens. It shouldn’t provision

 

[NicoC]

For the sake of saying I have tried the "approved" way of doing it I have performed the following
1. gone into extension 0276 and deleted the phone from the provisioning tab
2. Rebooted the phone
3. From the phones section assigned the unassigned phone to extension 0276
4. Before pressing okay to save the details onto the phone, change sbc address from 192.168.1.3 to .4
5. Let the phone finish its setup and reboot a couple of times

The end result is exactly the same where the extension has failed to register

 

[Alphabetic]

What is your network topology?

would it be possible for you to factory reset the router?

 

[ChrisC_3CX]

I have to agree with @kieferschild regarding the way the IP Phone provisions after being factory reset. It actually kind of sounds like you already have option 66 enabled on your network. In any case, this might not actually matter right now so I think you should check it at some point but not focus on it.

What I recommend focusing on is confirming that the 2nd SBC can communicate with the IP Phones. Theres a few things you could try, easiest one would probably be to:

1. Turn off the first SBC.
2. Go to Management Console >> Phones and reject all new phone requests.
3. Make sure no new requests came in to the "Phones" section and reset the IP Phone that you wish to connect to the new SBC.
4. Wait for it to reboot and check the MC Phones section. Do you see a new Phone entry for that IP Phone?
If yes, then that should be proof that at least multicast from the IP Phone was able to reach the 2nd SBC.

Note: You can turn on the 1st SBC once done.

 

[NicoC]

So I have figured out the issue (I just love taking over from previous IT companies). Unfortunately, this is a remote site and I have had no visibility of the physical network.

Turns out they ran a separate internet link with its own gateway also using the 192.168.1.xxx range. That is why when I was setting up the SBC on the Host it was not communicating correctly.

I really appreciate everyone's help. I knew I wasn't going crazy as another one of these clients sites required an SBC and it was up and working with phones changed over in about 30 minutes

 

[ChrisC_3CX]

So the IP Phones in fact were not communicating with the second SBC. In any case, glad to hear you identified the cause and got this sorted!

Feel free to start a new thread should anything else come up!