can't send or receive texts from mexico to canada

You may have to inquire of that cellular provider, if they require an international roaming plan

to use their services outside their coverage region. And ask what exactly that region is, too.

In some instances, if you travel between locations frequently, some users have additional SIM

cards for use with different regions cell providers and use other accounts. Or separate phones.

(Some travel with a cheaper phone in case it gets lost or stolen & leave other in safe-keeping.)

There are services that suggest you pay extra to get added regional coverage. IF you have a

specific set of issues in one iPhone, you may need to see the settings are correct for SMS

and MMS. While the iMessage service works between Apple iOS, that's not guaranteed. I see

on various occasions in the same region, I may get 'text sms' from another iPhone user. Then

later on the next one (in green balloon, or blue) gets through without whatever encoding or an

issue develops where iMessage isn't preferred; general SMS by default works. + You may pay

more for the SMS/MMS services, if your plan doesn't cover certain countries.

Roaming may be a reason why some services work while others do not. And in certain areas

the technologies and rules of law are different as well. ~ I don't have specific answer, though.

Good luck & happy trails! 🙂