In terms of roaming, we divide the world in two: the plan.com Europe Zone and the plan.com World Zone.
Europe Zone http://guides.plan.com/pro-europe/
47 countries including most you'd expect, and some that you might not!
World Zone https://guides.plan.com/pro-traveller/
Every country outside our Europe Zone, worldwide, including the United Arab Emirates, but with the exceptions of Kenya and Tanzania.
Before you travel, check out our handy roaming tool https://www.plan.com/roam
Tell us your destination, which tariff you're on and we'll guide you as to which roaming bolt-on(s) would provide the most cost-effective cover for your trip.