Unlocking a 4G LTE phone depends on the wireless carrier, explains Digital Trends. Wireless carriers may request the account holder's name, the account number associated with the phone, the device's IMEI, the phone number, the account holder's Social Security number and proof of a completed contract to unlock the phone.
Military personnel may go through a different process. If the customer is undergoing deployment and wishes to unlock the phone before the contract expires, the carrier may request official deployment papers.
Although Verizon claims that its phones are unlocked, Verizon phones operate on CDMA and not on GSM, which means that for the phones to function well with GSM carriers, such as AT&T and T-Mobile, they need GSM radios. Customers can request a SIM unlock by calling Verizon customer service as of 2015. Sprint phones also run on CDMA and require a similar unlocking process. However, Sprint iPhones cannot be unlocked.
To unlock T-Mobile phones, customers can call a customer service representative to make the request, explains Digital Trends. However, T-Mobile does not unlock phones that are reported as stolen, associated with accounts that are not in good standing or belong to customers who have already requested two unlocks within the same year.
Customers can unlock AT&T phones online if they have the IMEI, the AT&T phone's phone number and the account number associated with the phone. The phone cannot be stolen, and it must have already been paid for.