Foo - (Geek) Mobile phone/network/carrier compatiblity

All this talk about cell phones lately has got me wondering: Other than 'Unlocked' phones, is it possible to buy a model that one provider has, but switch service to another provider? Say, like Pcad's new toy from VZ, but run on it T-Mobile or a regional like US Cellular?

The big boys in the game have some pretty cool toys, but there are companies out there that offer better value on service.

It depends. There are two major cell phone systems out there in the US. Verizon uses CDMA, AT&T uses GSM. Sprint used to be CDMA but I think they're mainly GSM now after the Nextel merger.

Anyway, your phone needs to talk one of these languages on the specified frequency that the carrier uses. If you match those up, then you can take your phone from one carrier to the other.

Remember, some "regional carriers" aren't really carriers at all, but a retail front that rents capacity from one of the big carriers. If you can find out which one they rent from, then you can use that type of phone with their service.

Sprint is still on CDMA. As I understand it, CDMA phones are generally customized to a carrier, and don't transfer easily no matter what.

GSM phones are designed to be more portable, but Tmo and AT&T use different frequencies. However, many GSM phones sold today are "quad band" so they'll (theoretically) work with any GSM carrier in the world. But if you get a phone through your carrier, it will be carrier-locked until you unlock it. Once you've unlocked the phone, switching carriers is just a matter of popping out the old SIM card and popping in a new one.

Here's a good forum on figuring out phone-compatibilities, hacking and unlocking: http://www.howardforums.com

There are two technologies in the US: GSM and CDMA. Most of the rest of the world has standardized on GSM, though on different frequencies than in the US.

Sprint is CDMA. Verizon is CDMA.

AT&T, T-Mobile, and all other GSM carriers use the same frequencies in the same countries. In the US, that's 850 and 1900 MHz.

Most vendors 'lock' the phones they sell or give away to SIM cards for their network only, and do not allow 'unlocking' so that you can then use that phone with another carrier that uses the same technology (CDMA, GSM). I'm not talking about roaming here, I'm talking about taking a phone that you got, for example, with T-Mobile and then switching your service to AT&T with the same phone.

You can buy unlocked phones from independent resellers.