costs of using phone on overseas holiday?

Can anyone advise on how to keep in contact on a prepaid MTN phone while travelling? Once we've arrived in Canada I'll borrow a SIM but something always seems to go wrong with delays/connections so I need connectivity on the way there and back.

Samsung's Always On wifi will solve all my problems but how secure do you think it is? Do I even have to buy wifi, isn't it free at all the airports?

I'm just a bit worried about security.

Thanks

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