You need one with a SIM Card slot. From there, find a GSM carrier, buy a SIM card and slip it in. (T-Mobile, AT&T, and every European carrier is GSM).
It operates several GSM networks in Europe and the United States.
Unlocked phones are GSM phones that will work with any GSM carrier. A GSM phone works on AT& T, T-mobil and any other system that is GSM compatible. Most inetrnational cariers are GSM.
Unlocked phones can be used with any carrier, so it will support T-Mobile.
Gsm
It's a gsm/umts network. There's no cdma carrier in the Philippines.
AT&T and T-Mobile are carriers that are compatible with the Sony Ericsson W880i. You need a carrier that is GSM compatible. Carriers that are CDMA compatible, such as Verizon and Sprint, will not work with the Sony Ericsson W880i.
If the unlocked phone is an IDEN network phone then yes. If the unlocked phone is a GSM phone, meaning it was previously locked to a GSM carrier (i.e. AT&T, T Mobile) then it would not work on Boost Mobile as this carrier uses a different technology, which is not compatible with GSM based phones.
No
If you mean a Motorola RAZR phone locked to Metropcs, then it's not possible. AT&T runs on a GSM carrier, while Metropcs runs on a different technology, which is not compatible with GSM. So even if the phone is flashed, it would still not work on AT&T.
yes
In America, the two SIM-using GSM carriers are AT&T and T-Mobile. T-Mobile can only use it's EDGE network on an iPhone with a SIM Card needed.