This week, one of the least consumer-friendly practices in the U.S. wireless industry became (mostly) a thing of the past. The major carriers, and a few smaller ones, agreed to a code of conduct\u00a0that requires them to unlock customers' phones and tablets on request.\nUnlocked phones can be used on multiple carriers' networks as long as they're compatible with the networks' cellular technology, which is not always the case. Carriers have locked phones using software that could be removed by tech-savvy users, but the process wasn't exactly simple and it generally voided device warranties.\nThe agreement is administered by the CTIA, a trade group that represents wireless carriers, and it is voluntary, meaning there's no enforcement mechanism. The new pact says carriers must unlock a phone, or tell a customer how to unlock it, within two days of a request.\u00a0The carriers also agreed to post "clear, concise and readily accessible" unlocking policies on their websites.\u00a0\nOf course, there is a catch. If you're still under contract, or are in the process of paying for a device on an installment plan, you have to wait until it's paid in full to get it unlocked, or pay an early termination fee to switch to another carrier.\nHowever, some customers who have no intention of jumping to other carriers may want to unlock their phones when they travel abroad, so they can use their devices on compatible foreign networks without incurring sky-high roaming fees.\nCarriers could be reasonable about this and allow those customers who are still under contract to unlock their phones anyway. Unfortunately, AT&T will not make exceptions, a spokesman told me. Here's a link to the company's policy.\u00a0For T-Mobile customers, this is a nonissue because the company no longer sells locked phones. Verizon generally does not lock its phones even while the customer is under contract (here's the policy) and Sprint has not yet responded to my request for clarification.\nIf you are planning to travel internationally and want to unlock your phone, it's a good idea to contact your carrier well in advance.\nAT&T, Bluegrass Cellular, Cellcom, Sprint, T-Mobile U.S.A., U.S. Cellular and Verizon Wireless all signed the agreement, and additional carriers indicated they will eventually comply with the voluntary code, according to CTIA.\nThe code also has a number of additional consumer-friendly policies. From CTIA:\n\n"For example, signatories will adhere to the Code's 12 points, including commitments to disclose rates, additional taxes, fees, surcharges and terms of service; provide coverage maps; make customer service readily accessible; allow a trial period for new service; provide free usage alerts to avoid unexpected overage charges; and enhance transparency and disclosure of wireless providers' device unlocking policies."\n\nCarriers that voluntarily comply "receive the Seal of Wireless Quality\/Consumer Information, which they can display on the company's website and collateral materials.\u201d Most people have not heard of this seal, so the carriers aren't exactly taking a big hit if they don't comply, at least not yet.\nStill, the code is a step in the right direction, and it should lead wireless carriers to treat their customers with more respect.