OK, I have managed to sort this problem myself as the helpdesk couldn’t. The DV was working fine but suggested we couldn’t make calls - we had dial tone, but the far end appreared to be engaged. This was incorrect. We could receive call fine. Connecting the phone into the back of the hub we could make calls fine.
The issue was resolved by re-pairing the DV adapter with the hub - hey presto all fine again.
I will also point out initially we were unable to make calls from the DV adapter but that was solved by using the splitter (used for copper broadband and home phone).
I hope this helps others 😉
