VOIP handset issues

[#1]

Hi, have been gifted a new BT brand voip phone - have paired it with the hub, but phone handset says no voice service on hub?
I can use voip normally via laptop for work, what am I doing wrong? BT solotion is reboot the router (!) which I have done three times - is there a chance the phone is locked to BT only? Surely they can’t do that if it’s purchased?

[#2]

@whitesha  If you have a Plusnet Hub 2 it will have no Voip capability at all, and a BT Hub will only work with the BT Digital voice service so it is not going to work. Who is your Voip service provider? How do you use Voip on your laptop?