The short answer is Canada and Mexico, and only on one plan. Here's the detail.
Calling other countries
No plan includes calling other countries. See the article on calling another country from the US for what to do instead.
Roaming, plan by plan
- Go to portal.getflexmobile.com/storefront to see which plans include roaming.
What roaming covers on Flex Unlimited Plus
Everywhere else in the world
No Flex Mobile plan includes roaming outside Canada and Mexico. Travel Passes covering other countries are being developed but aren't available yet.
What works regardless of country
Wifi. On any plan, in any country, connecting to wifi gives you messaging, email and video calls. With wifi calling turned on you can also make and receive normal calls on your Flex Mobile number.
If your destination isn't covered
A travel eSIM from a third party provider, installed alongside your Flex Mobile line, gives you local data without touching your Flex Mobile service.
Don't confuse roaming with travel perks
Your membership includes discounts on flights and hotels through the rewards portal. Those are booking discounts and have nothing to do with what your phone does abroad.