Best Canadian prepaid for American making short infrequent trips

What would be the best and most cost effective Canadian prepaid wireless service for an American making regular but infrequent (twice a year) short (a week at a time) trips to Canada?

Only have American credit cards and an American address (though could use a friend's Canadian address in a pinch.)

Obviously there should be no recurring/monthly fees for the months the service would not be used. Preferably, but not absolutely necessary, keeping the same phone number between trips.

Been there done that.

Canadian cellphone service is very expensive. Your best bet is going to be T-mobile with roaming. Downgrade to the $3 plan when you're not in Canada.

@Chelle Are the Canadian prepaids more expensive than using a US carrier roaming in Canada? (If so, I'd wonder why more Canadians don't get a US carrier!)

If using a US carrier, would T-Mobile beat Cricket? And instead of downgrading to the $3 plan, would it be more cost effective to cancel and reorder as needed?

When we're in Canada our T-Mobile roams for free. And it works great.

Prepaid, in Canada, is very expensive. Postpaid might be better.

If you cancel you'll lose your phone number.