Will this phone work with my carrier?
By: Jason Vickery

As a sales associate for a popular cellular carrier, I have run into many customers trying to activate an incompatible phone.  Whether it is a used phone or a new phone purchased outside the retail stores, here is a guide to making sure that phone you purchased will work with your carrier.
There are two three categories of cellular carriers: GSM, CDMA, and iDEN. 

CDMA
CDMA uses major carriers such as US Cellular, Sprint and Verizon.  With CDMA carriers, each phone is locked permanently to that carrier!  Each phone has an ESN (Electronic Serial Number) which is usually found behind the battery back.  This number is how the carrier identifies the phone. 
Although the same brand and model number may be available to multiple carriers, they will only work with the specific carrier it was made for. 

Example: Motorola Razr V3m Silver
US Cellular, Sprint and Verizon have this phone available.  Although they cosmetically look the same, the menus, programming procedures, and data communication are entirely different between the three.  If you try and activate one from another carrier, it will not activate or perform correctly.

GSM
GSM carriers are much more plentiful overseas.  Two popular GSM carriers in the US include AT&T (Cingular) and T-Mobile.  GSM carriers use SIM cards; which are little chips that include all of your contacts and phone information.  SIM cards can be removed and inserted into another phone, immediately activating it. 
SIM cards and flash/memory cards are not the same.  Flash or Memory cards hold media such as pictures, music, and videos.  SIM only hold contacts and vital phone information!  Flash/memory card types include SD, MicroSD, MiniSD, TransFlash, xD, Compact Flash, Memory Stick, and many others. 
GSM phones are usually locked initially to a carrier but are easily unlocked.  Unlocked is a term used with GSM phones making them cross compatible with other GSM carriers only. 

Example: Apple’s iPhone
The most current example of unlocking is the Apple iPhone.  It is exclusively available from AT&T, but can be unlocked to work with other GSM carriers.  Although it will make telephone calls, the data service compatibility may or may not work.  There is absolutely no way to get an Apple iPhone to work with CDMA carriers. 

iDEN
iDEN is a special signal to Nextel with their Walkie Talkie (Chirp) service.  It uses a SIM card but does not have the ability to transfer from phone to phone.  iDEN uses its own set of towers and are not cross compatible with any other carrier.

Conclusion
Not all sellers on eBay are advertising correctly, leaving the consumer to find out the truth the hard way. 

• On a CDMA carrier, the phone has to be specifically produced for your carrier.
• Remember: with a CDMA carrier, the term unlocked doesn’t apply. 
• GSM carriers need to have a phone made for that specific carrier or be unlocked.  
• If you have any doubts about if your carrier is GSM or CDMA, call your carrier’s 800 number or go visit a local store or kiosk.