New to Apple Core - Deciding to get an iPhone

All smartphones that I've owned has been Windows Phones. As you can tell from my username, I am a MS fanboy. However I do want to try all platforms at some point, but I want to keep my WP by my side at all times.

My question is: I know people have multiple devices and just switch SIM cards back and forth to whatever phone they want at that time, but I want to switch to and from my WP to an iPhone without the hassle of my carrier. Is this possible? This may sound like a simple question, but I have no idea.

I want to do this because I'm interested in purchasing a MacBook in the near future and it would be best to have an IPhone around to compliment it.

Thanks again.