Do I need to unlock a used iPhone to use it?

[chiroken]

Hello, we are looking to buy a used iPhone 5C, 5S or 6 for our daughter. We do not intend to immediately have her use the phone as a 'phone', moreso as an iPod. We want her to be able to use apps that will no longer work with iPhone 4/4s and want her to use the phone just on wifi. We are not yet planning on adding her to a data plan.

If we buy a used iphone that is locked to Telus Canada, will it still work on wifi without being on a cellular plan? Does it have to be unlocked?

How do we know if it will need a new sim card? I don't understand this.

Thanks for your assistance, I don't really know how all of this works.

[Nighthawk]

Hello

You do not need a SIM card for it to effectively function like an iPod, with apps limited to wifi only. You'll only need a SIM card when you plan to use it as a phone. If it is locked to Telus, that just means it will only work with Telus at present. It will need a new SIM card when you plan to use it as old ones expire after 45 days of inactivity I believe. If you wanted to use it with another carrier, you would have to get service with Telus for a minimum period before it could be unlocked as noted on Telus' unlock page.