Starlink connected phones can't register with AWS Hosted 3CX

[wright]

Self Hosted, Version 20.0 Update 3
Static IP
Phones are Fanvil X6U-v2 with updated firmware.

Main office was destroyed by Hurricane Helene, and we are at a temporary warehouse trying to use Starlink to connect 4 phones.

At a location with cable internet, I can successfully connect these same phones to the hosted 3CX, and I can make calls.
Soft phone to 3cx through cell service also works fine to the hosted 3CX.
I can access the 3CX Admin Console from the Starlink location local network.

I tried deleting the IP phone for a user and added it back.
The provisioning file was successfully generated and delivered.
The phone reboots and BLF entries are updated.
But, the phone gives SIP Register error.
Under Voice & Chat the Fanvil x6U-v2 (102) (3CX SBC) Router Phone status square stays red.

No new entries in the IP Blacklist

Under Users, I can Edit User 102 then check the IP Phone tab and there is NO Entry in the Local IP field.
I was able to get the local IP from the phone Status and could successfully access the Phone via https using the web console password updated in the IP Phone tab.

Starlink is 'Standard' model and is in 'Normal' mode, not pass-through.

In the Starlink phone app to configure, the connected phones are listed with local IP and manufacturer.

Suggestions please, we would really like to get this working.

 

[Guillaume Bourgeois]

Try disabling IPv6 on Starlink.

 

[wright]

I don't see a way to disable IPv6 at the Starlink Router.
I found "Automatically bind to IPv6 adapters" under Network in 3CX, so I unchecked that. Restarted 3CX Phone System 01 SIP Server. Deleted IP Phone. Added back with MAC address, & Direct Connect.
Powered phone off & back on.
Still no good.
"SIP Register Failed" on screen of phone set.

 

[Guillaume Bourgeois]

You should reach out to Starlink for assistance.
This clearly isn’t an issue related to the 3CX PBX.

Starlink might already have a solution for this.
You’re probably not the only one trying to make a SIP application or basic TCP/UDP communication work.

My first thought was IPv6 because it's not uncommon for it to cause issues when not properly configured. But if you can't disable IPv6 on Starlink, the best idea is to contact your internet provider...
Because you'll face the same issue with other services, like VPNs or any non-HTTP/HTTPS TCP service.

 

[wright]

In case it's helpful to anyone, here is the update. The main problem was not in my original description. We were trying to use WiFi with the phones. Yes, I know WiFi is not supported by 3CX, but it can work. In this scenario, there is no premise wiring. Wired does provision & does operate with Starlink - even in normal mode, not pass-through. It isn't great, there seems to be a delay when dialing and when first answering. But, it does work.
The 3CX app on mobile phones works better with Starlink WiFi, and is an acceptable solution.