Slightly odd request but I’m struggling to find it myself. I live in Luxembourg and our company has staff in about 6 countries. I’d like to get a single mobile provider to cover all the countries and manage the contracts from a single account rather than having phone providers that bill us in each country.

Any of the big boys will do it, in the UK anyway – should be same for you. Just call your local provider, and if they don’t, call another one.