Several readers have various questions related to cell phone networks and carriers. We take an in-depth look to come up with some answers.
AT&T Wireless
AT&T Wireless owns and operates a GSM 850/1900 MHz network. The safest way for AT&T customers to buy unlocked phones, is by choosing phones that are supporting both frequencies. AT&T's 3G network operates on the same frequencies. In addition, AT&T has licensed portions of the 1700 MHz frequency (AWS spectrum), which will likely be used to enhance its 3G capacity in certain areas.
Coverage map
AT&T phones
Unlocked GSM 850/1900 MHz phones
Unlocked 3G 850/1900 MHz phones
T-Mobile
T-Mobile USA owns a GSM network operating on the 1900 MHz frequency. To further enhance its network coverage, the carrier is also seamlessly using AT&T Wireless' 850 MHz frequency when their own network is not within reach. Since most European handsets are supporting GSM 1900 MHz, T-Mobile USA's customers can pretty much choose from any European handsets available via online retailers like Amazon. Just make sure to check out T-Mobile's coverage map first, which distinguishes T-Mobile's 1900 MHz coverage from the 850 MHz roaming. T-Mobile does currently not offer 3G, but a network is currently being deployed on the 1700 MHz frequency (AWS spectrum).
Coverage map
T-Mobile phones
Unlocked 1900 MHz phones
Sprint
Sprint owns and operates a CDMA network operating on 800 and 1900 MHz frequencies. Only phones that are originally purchased with a Sprint subscription will work on this network. In order for a Sprint phone to for instance work on Verizon Wireless' network, the phone would need to be flashed with firmware from Verizon Wireless and tested on Verizon Wireless' network. Sprint uses the 2100 MHz frequency for its EV-DO data services, and is currently also deploying a Mobile WiMAX network on the 2500 MHz frequency.
Coverage map
Sprint phones
Verizon Wireless
Verizon Wireless owns and operates a CDMA network operating on 800 and 1900 MHz frequencies. Only phones that are originally purchased with a Verizon Wireless subscription will work on this network. In order for a Verizon Wireless phone to for instance work on Sprint's network, the phone would need to be flashed with firmware from Sprint and tested on Sprint's network. Verizon Wireless uses the 2100 MHz frequency for its EV-DO data services, and will soon begin trials for its 4G network to operate on the 700 MHz frequency.
Coverage map
Verizon Wireless phones
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