phone service

Obviously we use GSM 900 as u all aware of..and using only in one network provider.
Here,they have different wireless service carriers and different technologies are being used to provide the service.
No government telecom service.All are private companies.I was told that verizon is the largest net work here in this city and they are using so called'CDMA' service.Reception is always strong and have good reputation to public though they are a bit of expensive carrier. let me share you what i got from www.cnet.com here
they said..
Because the United States uses two cell phone technologies, even an unlocked phone does come with some restrictions. It all depends on whether your phone uses GSM or CDMA.

GSM
The first cell phone technology, called GSM, is used by T-Mobile and AT&T. GSM unlocked phones give you the most freedom because they use a small, plastic chip called a SIM card, which typically is located behind the phone's battery. SIM cards are issued by your carrier and contain your identity as a subscriber. When you insert your SIM card into a phone, that handset is activated and assumes your number.

While locked phones will accommodate SIM cards only from a certain carrier, unlocked phones will work with SIMs from any provider. So, if you're a T-Mobile customer and you pop your SIM into an unlocked handset, you'll be able to make calls as normal. But if you put that same SIM into a locked AT&T phone, you'll be able to dial only emergency services.
An unlocked GSM phone is also advantageous to frequent globetrotters. In most countries throughout the world, you can buy a prepaid SIM card from a local carrier and use it in an unlocked handset. That phone will then have a local number for that country, which can save you a lot on international roaming charges. For more information on using a phone abroad, check out our Quick guide to world phones.

CDMA
The second major technology, which is incompatible with GSM, is called CDMA. Verizon Wireless, Sprint Nextel, and a number of regional carriers such as Alltel and U.S. Cellular use CDMA. Though CDMA phones also can be unlocked, it's not as easy to transfer them to another carrier because they don't use SIM cards. Without the SIM card, you must ask the new carrier to activate the phone for you and assign it to your number. Not only does that involve extra steps on your part, but also there's no guarantee the carrier will oblige you. While Verizon Wireless will now activate any CDMA phone, the remaining CDMA carriers may not activate a handset that they didn't sell you.
CDMA customers also don't get same benefits when traveling abroad. CDMA is used in far fewer countries than GSM, so even if you have an unlocked CDMA phone, chances are greater you won't be able to get service abroad, much less have it activated.

So to sum it all up, unlocked phones can be quite beneficial if you use GSM, the benefits are more limited if you use CDMA. That's why we'll be focusing on GSM for the remainder of this feature.
In brief,i personally found out CDMA is better in reception especially in the basement and buildings.It may not be the same experience as i did for some users.
Phone charges are different between network providers.They sell data service,internet service,text messaging services .All are extra value added services.
You would have to buy minutes per month like 700 minuses per moth for 70 usd.weekends free..late night like 9 pm to 7 am free..etc..
you will have to make an agreement with network provider for a period of time like 1 year of 2 years contract.They offer basic camera phones for free depends on how u make an agreement with them.They can even provide good smart phone with reduced price.Fpr example,now iphone..
if u r going to buy unlock iphone from apple,u will have to pay like 600 bucks..But if u r buying unlimited data and voice service from them u can get iphone with price of 200 for 8 gb and 300 for 16 gb.monthly basic bill will be like i26 for family and for individual it will cost u like 70 bucks a month.
Hope i share something about phone service with my little knowledge..
Enjoy knowing different practices in different places.
best of luck friends