Old cellphone question

you can simply rent a portable wifi device at the Canada airport, which local sim card is provided, and then use your existing mexico mobile to connect to that portable wifi device. That give you a hassle free

Did you recall that you could use the old phone in US?

If yes, it should work in Mexico also provided that your carrier in Mexico still supports 2G network. 2G was retired in many countries. However, developing countries like Mexico may still use 2G for telecommunications.

Not all carriers are the same, you need to ask them.

https://www.gsmarena.com/network-bands.php3?sCountry=MEXICO

You can get prepaid SIM cards at major airports and most drug stores / department stores. The SIM card will tell you what ISP you have but since it is prepaid it doesn't really matter.

Do you have a Roaming plan for your current phone?  That may work better in the long run. I have one phone and I roam with it.

Depending on your current phone type, you may be able to put the sim card from it directly into the old Nokia. However, most modern phones use either a micro sim or more usually a nano sim. The Nokia will support either the nano or micro sim with a sim adapter, so if you have one, just try it. The beauty of SIM cards is they contain your phone number and account details (and often phone numbers), so putting your existing SIM card in the old phone would allow you to call someone from your number but from the Nokia as a device.
If you find it works, then when you travel, call into a cellular providers kiosk at your destination airport and buy a new sim. Be warned though, your Nokia is unlikely to be able to access the internet, and will probably be only useful for making and receiving calls and sending and receiving text messages.

Your phone will work anywhere 2G GSM works.

So the real question will relate to where you're traveling in Canada.

Best first check for 2G coverage. This will tell you how well your phone will work.

Tip: You can purchase a TracFone with 3G coverage + 1000-3000 minutes good for one year for $30 USD of Amazon.

You'll save time + trouble, just purchasing a TracFone in Canada + have it shipped to wherever you're staying.

Hi- I just want to use it to have a local phone number so people can call me. My Mexican cell works in the US and Canada, I can access internet, phone for free anywhere in North America. But in Calgary, I want people to be able to call me locally, So I don't need internet, just phone and texting.  David, I'll investigate the Tracphone, thanks!

thanks, everyone!

You are very welcome and I was happy to help (I live in Canada and travel all over so I empathize with your needs)