You will need to look at which phone you want to buy. If they state a carrier name such as Sprint or AT&T then that particular phone is locked to that network and a plan must be purchased. You do not need a 2 year contract plan to use this phone however, signing a 2 year contract lowers the price of the phone. Buying it outright without a contract is more expensive but carriers have deals for signing up for a plan and the phone is technically loaned to you for a monthly price.