To unlock a device for free, a mobile phone owner can submit a request to his service provider. AT&T, Sprint and T-Mobile give individuals the option to unlock their cell phones online. Generally, users should wait until the end of their contract term for greater success.
AT&T devices can be unlocked by completing an online form on the carrier's official website. Users should know the IMEI number, along with information on the current or previous owner. T-Mobile and Sprint customers can request to have their phones unlocked by initiating an online chat with a representative through the companies' official websites. Alternatively, they can call in their request by pressing *2 on a Sprint device or 611 on a T-Mobile phone. Verizon customers can request a SIM unlock by contacting the company by phone.