Yes, data roaming. Although the network in some foreign (Canadian) areas do not always deliver the full performances promised in the (Singapore) plan.
Yes, people in Canada have to dial long distance to "Singapore" when calling her, even when she's in Canada. Not a problem for her since all her friends and family in Canada have the same plan - they can all dial anywhere in the roaming area to anywhere in the roaming area at not extra cost. Most of her calling is dialed out, which is a non-issue - or is incoming from others on the Singapore plan, which is a non-issue.
Hardly "forced to subscribe to a Canadian service anyway". People with important calls will pay the long distance costs or will find other ways to contact her. She can return calls without long distance costs. It seems like the scary deal-breaker on the surface, but it turns out that these limitations don't really apply much in the modern world - since texts and emails are essentially free - since people who think their calls are important (to you) will always find a way to contact you, to leave a message with a way to contact them back, etc.
The scary limitations come from Canadian providers with strictly in-Canada service and very limited roaming options. As I suggested above, foreign operators often have far more generous roaming service offerings and collaborations, their customers can enjoy full phone service across multiple countries in large geographic zones.
I described a Singapore-based operator which services most of Asia and the Americas and almost everything in between. But there's others (I don't know much about) who service Europe/America, Europe/Asia, Africa/India/Asia, etc, and some of these might include Canada as well.
I know that these sorts of international calling SIMs or multi-region operators almost always use the Rogers network to provide coverage when in Canada.
