If i switch carriers will I have to restart my phone?

I want to switch carriers. Right now I have metro pcs but I'm planning to switch to T-Mobile. I got a new iPhone about 2 months ago so if I switch carriers I'm not looking on buying a new phone. So will I have to restart my phone to switch? Will I loose anything like pictures, apps, or stuff like that?

To use the old phone on a new carrier, you need to get the phone unlocked from the carrier. Normally they do this for free while you are still a customer, and your account is paid up and the phone is paid for. Otherwise you will have to pay to unlock the phone, to use it on another carrier.

You should just be able to swap the SIM cards. If that doesn't work, then you'll have to get your phone unlocked - look up "phone carrier unlock" for that.