Q: Which network does my cell phone company use?
A:
- Alltel: CDMA
- Cingular/AT&T: GSM
- Nextel: iDEN*
- Sprint PCS: CDMA
- T-Mobile: GSM
- U.S. Cellular: CDMA
- Verizon: CDMA
Note: Other small cell phone service providers have networks that operate on one of the technologies listed above.
** iDEN is a technology that only Nextel uses.
Q: What is GSM, and if I have a GSM phone will it work on any GSM service?
A: GSM stands for Global System for Mobile, and is a type of Time Division Multiple Access. The two are different enough not to be compatible, but both rely on the same theory of splitting multiple calls into fractions of time.
GSM phones have a SIM card inside the phone (not much bigger than the tip of your thumb to the first knuckle) that contains subscriber details and security information. SIM stands for Subscriber Identity Module, and it tells your carrier's network which phone is which, and how to bill you for the calls you make. Software locks on these phones prevent you from using a SIM card that belongs to a competitor.
Ask your current cell phone company, or one you are considering, whether it locks the phones it sells and whether the company will remove the lock. A few carriers have indicated they will unlock the phone after you have been their customer for a few months.
Q: What is CDMA, and if I have a CDMA phone will it work on any CDMA service?
A: CDMA stands for Code Division Multiple Access. It's another method of digitizing and compressing wireless phone calls to allow several calls to share the network at the same time.
As for taking your phone to a new carrier, maybe. Some CDMA carriers will let you take a phone from a different CDMA carrier, particularly if they sell a similar phone themselves. These phones are sometimes locked. It always pays to check with the carrier before you sign up.
Q: What is TDMA, and if I have a TDMA phone will it work on any TDMA service?
A: TDMA stands for Time Division Multiple Access. It's a method of digitizing and compressing wireless phone calls to allow several calls to share the network at the same time.
Now, can you take a TDMA phone with you? Probably not. No technical barriers exist that prevent this from happening, but big cell phone companies typically lock the phone. Whether or not your phone is locked, chances are you'll need the code from your original carrier to move to a new carrier.
