- Unlocked phones give users certain freedoms when choosing a cellphone and a carrier -- for instance, if a user wants to switch to a phone not typically offered by their cellular provider, they can choose to purchase an unlocked phone and simply switch over their SIM card. Mobile providers that use Code Division Multiple Access are not compatible with unlocked phones, as they do not use SIM cards. Providers that use SIM cards use the Global System for Mobile Communication. In the U.S., AT&T and T-Mobile both use GSM; GSM is the standard in Europe. Sprint, Verizon Wireless and US Cellular use CDMA.
- It is not illegal to use an unlocked phone, nor is it illegal to unlock a phone that you own. However, in the U.S. cellular providers are not required to sell unlocked phones, nor help you unlock a phone that you own -- though some may choose to do so. The legal right to unlock a cellphone you own was provided in November 2006; prior to this, unlocking cellphones was considered copyright infringement as per the Digital Millennium Copyright Act.
- The greatest benefit to an unlocked phone is the ability to use a new phone without purchasing it via your cellular provider, a process that often involves renewing contract lengths and can incur further fees. You also have the freedom of taking an unlocked phone to any service provider that supports it. Unlocked phones can be used internationally by swapping the SIM card with a new one in the country you're visiting, which helps cut down costs of international calling while your abroad.
- Unlocked phones are typically more expensive, sometimes two or three times as much than when purchased with a carrier and a mobile contract. Due to the limitation of carriers that use GSM, even with an unlocked cellphone, your carrier options are relatively limited in the U.S. Some phones include features only available with specific carriers, which may not be available when the phone is unlocked and taken to a new mobile carrier.