US wireless carriers must adhere to a strict cellphone unlocking policy, following a ruling from the Federal Communications Commision on Thursday. All major carriers in the US have signed on to the policy, and the agreement will ensure customers are notified when their smartphones are eligible to be unlocked. 

The policy follows a law that went into effect in January that essentially made unlocking a cellphone illegal in the US. Technically it could have been done under the law, but it was a difficult process. It outraged many in the telecom industry and prompted a White House petition to change the ruling. Now, with the FCC stepping in, the unlocking has gone in favour of customers. 

Carriers in the US must follow strict guidelines under the policy. On their website, the carriers have to disclose their policy for postpaid and prepaid mobile wireless device unlocking, provide notice through means like a text message or an email, and have a response time of two business days after receiving a request to unlock. Military personnel who are in good standing with the carrier and request to have their cellphone unlocked will have their request accepted, no matter where they are in their contract.

A locked cellphone only works with one specific carrier, often associated with two-year contracts in the US. This can be troublesome if a cellphone user wants to go outside of the country or move to another carrier that supports their cellphone's bands. 

The guidelines will be going into effect over the next year, the FCC said, but carriers must have three of the guidelines implemented within the next three months. 

It’s worth noting that Verizon offers its iPhones unlocked out of the box, letting customers take them globally without any hassle. Most carriers unlocks handsets that aren’t currently under contract. This is still acceptable under the FCC ruling, but must be clearly stated by carriers.

UK carriers will usually unlock your cellphone for free or a small free, but they still require you to finish your contract.