In some countries, like the US, mobile phones bought on contract with a carrier are usually locked to that particular carrier. This means that you will not be able to use it with another carrier unless the original carrier unlocks the device. This is pretty restrictive, although lately carriers have been making an effort in becoming more customer-friendly.
Sprint is expected to follow suit and according to a recent FAQ on Sprint’s unlocking policy, the carrier revealed that they are working towards making their smartphones SIM unlockable, at least as far as devices that have been developed and launched on or after the 11th of February, 2015. This means that we still have quite a long way to go but we guess it’s still progress, right?
It should be noted that because carriers such as Sprint and Verizon relied on different radios compared to AT&T and T-Mobile (CDMA and GSM respectively), it means that your phone is basically locked to their network, or at least only usable on another CDMA network. By allowing phones to be SIM unlockable, it will allow customers to bring their phones to other networks in the future if that’s what they want.
As it stands, Sprint’s current lineup cannot be unlocked, possibly due to the way that they have been manufactured, which might explain why this move is only taking place next year where a batch of fresh new devices will be unlockable, but like we said, better late than never!