SIM Card Switching Question

[Streat]

Hello, my girlfriend and I have an HTC M8 and Iphone 6 with Verizon and Sprint respectively. I was wondering if I could switch either of these SIM cards to an old blackberry pearl from T-Mobile or Sprint for when we go out so we don't have to worry about breaking an expensive phone? Thank you!

 

[Titillating]

I think they use a different sized SIM card (iPhone and M8 SIMs are smaller), but you can get a cheap adapter which should work just fine. Something along these lines: http://www.walmart.com/ip/SAdapter-Nano-SIM-Card-to-Micro-SIM-Card-Adapter/24230265

Have heard reports that some poorly made adapters can damage the SIM card slot though. Something to keep in mind.