What is GSM?
GSM is the most widely used cellular network in the world.
GSM (Global System for Mobile Communications) is a wireless technology that is used my cellular carriers in the USA and around the world. It is extremely popular because of a large network of international roaming agreements. This means that a compatible GSM phone can be used conjunction with 650 carriers in 210 countries/areas of the world, where a roaming agreement with your home network is in place.
Which carriers use GSM in the USA?
Cingular and T-Mobile are the largest GSM carriers in the USA.
Verizon and Sprint operate on the CDMA network, and Nextel operates on the iDEN? network. In the USA the largest GSM carriers are Cingular, AT&T Wireless (Cingular Blue) and T-Mobile. In addition to this, there are over 50 regional GSM carriers providing coverage for smaller and more remote areas. Most of these carriers have roaming agreements with each other to provide greater coverage for their subscribers.
Only GSM phones can work with GSM carriers.
What are frequency bands?
Carriers operate on specific ranges with the GSM frequencies.
The GSM network consists of multiple frequency bands on which carries operate. Carriers work on single or multiple frequency bands, which are usually issued by the government. The four frequency bands in use by the GSM network worldwide are 850, 900, 1800, and 1900 MHz (MegaHertz). In the USA the frequency bands in use are 850 and 1900 MHz; different countries use a different combination of these four bands.
DualBand and TriBand phones can operate on 2 and 3 frequency bands respectively. A Quadband phone provides maxium coverage as it can operate on all 4 frequency bands.
What is a ?sim free? or ?unlocked? phone?
An unlocked GSM phone is not locked to a particular carrier.
When you purchase a GSM cell phone with a new service plan, the phone is locked to that particular carrier. This means that the phone will not work when you insert a SIM card from another carrier in order to use that network on your phone. Carriers usually lock phones usually to prevent subscribers from using the phone with a competing carrier.
?Sim free? refers to a phone that is bought without activation or a service plan. A phone bought with an activation plan is heavily discounted because the carrier can recover the cost through the revenue guaranteed by a 12 month (or longer) service contract.
How do I use my existing phone plan with an unlocked GSM phone?
Insert your SIM card from your carrier into your cell phone
If you are with a carrier which uses the GSM network, you will have been originally provided with a SIM card. The SIM card contains all the relevant information for connecting your phone to the network including your existing phone number, in addition to any contacts you may have saved.
You can find instruction on how to remove and insert you SIM card by reading the manufacturers manual.
Can I use my cell phone abroad?
Certainly, if your phone is compatible and your carrier allows it.
To use your phone abroad you must first check that your phone can operate on the frequency bands in use by you destination country. This information can be provided by calling your carrier. You may also need to make a request with your carrier to enable international roaming on your service plan.
When abroad your cell phone will be working on a foreign carrier which has an international roaming agreement with your home carrier. Any calls made or received abroad will normally be substantially higher than usual. Please consult your carrier for more information on your roaming call rates.
What is an IMEI number?
It is a serial number for you phone.
An IMEI (International Mobile Equipment Identity) is a unique 15 digit code used to identify an individual GSM cell phone to a cellular network. You can usually find the IMEI number on the exterior of your phone?s original box and also on the back of the phone with the battery off. An easier way is to simply enter *#06# and the IMEI number will be displayed on screen.
