Sprint announced yesterday that beginning next year, it'll make all of its devices unlockable for use on other carriers in the United States. In an update to its unlocking FAQ page, the company says: "Sprint is working to ensure that all devices developed and launched on or after February 11, 2015 are capable of being unlocked domestically".

This means that you'll soon be able to request an unlock code for any of the company's devices so that you can use your phone with other domestic carriers. At present, Sprint's customers do not have this option. The carrier, however, provides the service for use on foreign networks.

Although it's a move in the right direction, there are some limitations. The carrier says it can't unlock some devices, like iPhones made with a SIM slot in the past three years, because of the way they're designed. Moreover, the unlocked phones may not retain all of their functionality, and in case they do, the other carrier still has to support the device and all of its functionality.

The move is part of an agreement that the FCC and five major U.S. wireless carriers, including AT&T, Sprint, T-Mobile, U.S. Cellular, and Verizon Wireless, signed last December. Other US carriers who were party to the agreement will ikely follow suit soon.

Below are relevant portions from Sprint's unlocking FAQs:

I’ve been told by another carrier that Sprint needs to unlock my SIM slot in order to use my phone on the other carrier’s network.

For eligible devices, Sprint will unlock the SIM slot, to the extent that a device SIM slot is capable of being unlocked. It is important to note that not all devices are capable of being unlocked, often because of the manufacturers’ device designs, and that even for those devices capable of being unlocked, not all device functionality may be capable of being unlocked. Specifically, devices manufactured with a SIM slot within the past three years (including, but not limited to, all Apple iPhone devices), cannot be unlocked to accept a different domestic carrier’s SIM for use on another domestic carrier’s network. Sprint has no technological process available to do this. In accordance with Sprint’s voluntary commitment contained within CTIA’s Consumer Code for Wireless Service (“Unlocking Commitment”), Sprint is working to ensure that all devices developed and launched on or after February 11, 2015 are capable of being unlocked domestically.

I have been told that my device is not capable of being unlocked and/or does not have a corresponding MSL code.  What can I do?

Many devices that have been manufactured for Sprint simply are not capable of being unlocked, or will not have a corresponding MSL Code. For example, Sprint-branded iPhones have been manufactured in a way that prevents them from being unlocked to allow the device to activate on a different carrier’s network in the United States. This is because, prior to the development of the voluntary commitment contained in within CTIA’s Consumer Code for Wireless Service (“Unlocking Commitment”) carriers were not required to, and many carriers did not, develop their devices to be capable of being unlocked. Sprint strongly encourages owners of such devices to consider Sprint’s Buyback Program, which may enable them to trade in their old devices to receive an in-store credit towards the purchase of a new device or to receive an Account Credit. For more information, visit sprint.com/buyback. To help resolve this problem, Sprint has committed to ensure that all of its devices produced after February 11, 2015, are capable of being unlocked.