Verizon uses CDMA rather than GSM, but all of Verizon’s 4G LTE and almost all of its 3G devices come with an unlocked SIM card slot. Due to the unlocked SIM card slot, most devices do not require unlocking in order to be used with another wireless carrier.
Most all Verizon devices are SIM-equipped and can be used on other wireless networks without being unlocked as required by AT&T, T-Mobile, Sprint and other GSM brands; however, the amount of LTE support varies. Even though most Verizon devices are unlocked, many carriers use different frequencies and air interface so Verizon does not guarantee that devices purchased through them will work for another carrier’s network.
The only phones that Verizon makes that do require an unlock are the non-iPhone global-ready 3G phones. These phones come with locked SIM cards that can be unlocked at the user’s request or by unlock code. The simple programming codes used to unlock these phones are either “000000” or “12345”. The user guide to the phone should answer any questions the user may have about unlocking a phone, but Verizon also provides instructions if the user calls either 611 or (800) 922-0204. The company also offers SIM unlocks for users who cannot complete the unlock process themselves. The SIM unlock request number is (800)-711-8300.