I don't know what DrGeoff's phone's problem is, but with regard to the OP's situation:
Officially, Google Voice is a USA-only service, meaning
inbound numbers are not available nor officially supported for use outside the USA. However,
outbound calls can typically be made from any country where Google Voice service is available. Here is a list of the countries where you can't make calls:
https://support.google.com/hangouts/answer/3205646 (expand the sections on the linked page to see the list).
You have a working Google Voice number. Use that one. There is no reason to have a Google Voice account registered to an OBi without an inbound phone number. If you want to make an anonymous call, prefix the call with *67