Unable to call a landline number

[slates149]

So here’s the problem I have which I am completely puzzled by and have tried everything I can think of to solve it. 
My mother in law has just changed her broadband provider to BT. As part of the super fast broadband service, she has now got VOIP landline phones using the same number she had with her previous, copper wire landline provider. 
However, since the change I CANNOT call her landline from my Vodafone mobile. It just gives 3 beeps and goes dead. What’s more strange is all my family are able to call her from their mobiles but not me. I am the only one with Vodafone. I have tried deleting her contact and dialling the number, rebooted both my phone and her router, had BT check that she hasn’t inadvertently blocked me and other things but no joy. It’s driving me mad!!

I tried to talk to Vodafone about it but they just assumed I couldn’t call anybody. That isn’t the case, I can call other landline numbers but not hers!!

PLEASE HELP ME

[donnyguy]

It does sound like an issue with the number port from the copper network to the IP platform used by BT. 

They need to call BT and report they're not receiving incoming calls from certain networks since their port. BT will take care of fixing it. It's not uncommon.

[slates149]

Thanks @donnyguy 

A BT engineer is booked for Tuesday. As you advised, they believe it’s exactly what you said. It’s happened during the porting of her number from the old copper network to the new fibre one. Just so happens I’m affected (there may be others not known to us). 
Thanks again for the response 👍