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Cellular Phones/question about phones and contracts


Hello DebiN
i got some questions about the phones that are using in USA i mean all phones it doesn't matter what company i was little bit confused when i came first because i always use GSM(sim card) phones i know there is CDMA(contract) phones but here in USA so many deals with this phones. So this is my question about GSM phones.
1. If i will buy the phone T-mobile or AT&T(with SIM CARD slot) can i unlock it in another country and use it with other SIM CARD?
2. Also i don't know how to find out the phones with SIM card slots(GSM) because everywhere is just the contract, prepaid, no-contract phones.
3. And this question is killing me because i can't figure out with this almost two weeks it's about unlocked phones and no-contract phones. unlocked it means GSM and can be used with Sim Cards i got that but no-contract some of my friends they telling me that some of the no-contract phones can be unlocked and have Sim Card slots so am confused. what should i do? i asked the sellers, no exactly answers. i don't know, i am confused...
If it possible can you explain me all about this?
Thank you

All T-Mobile and AT&T phones are GSM. All Sprint and Verizon phones are CDMA. If you purchase a GSM phone you can have it SIM unlocked and use it outside the US with a local SIM.  You can have the carrier unlock a post paid phone after 90 days but you can pay a third party to unlock any phone. All GSM phones have SIM cards. I would recommend against buying a phone that uses a micro or mini SIM unless the country you plan to use it in has these size SIMs.  That's the only gotcha I would be concerned with.  Hope this helps.  

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I can answer questions on cellular phones, the physical device, the network, contracts, billing, ordering, porting and what to look for when purchasing cell phones. I am located in the United States. I am an expert on BlackBerrys, Treos, HTC devices and iPhones as well as cellphones and aircards. I have over 15 years of experience in both the wireless and wireline world with the carriers. I have a lot of knowledge regarding the wireless providers - their services, prices and policies, both GSM AT&T and T-Mobile) and CDMA (Verizon, Sprint/Nextel). I am very familiar with the individual devices and their specifications. I can also answer questions regarding BlackBerrys, iPhones and other PDAs, both Palm-based and Windows-based. I can troubleshoot most any problem someone is having with their cellular device or with the provider.


Over 20 years in the Telecom industry working for the carriers with individuals, small business, medium business and large corporations(Fortune 500). Also worked as a professor in Maryland for 10 years teaching telecommunications.

I belong to several organizations

Master's in Telecommunications

Awards and Honors
Received several awards for papers that I have published over the years

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