Popular networking technologies used by wireless operators in the United States are:
  • CDMA - Code Division Multiple Access
  • GSM - Global System for Mobile Communication
Generally speaking, CDMA carriers have better coverage in the Unites States. GSM was developed in Europe and has a strong foothold there.

If you travel a lot you should choose a a tri- or quad-band GSM world phone. Look for a GSM 900/1800/1900 or a GSM 850/900/1800/1900 phone.

GSM Facts

GSM is more widely used than CDMA, with service available in more countries around the globe and if want a true world phone, GSM is should be your choice.

GSM supports high speed data via GPRS (20-40 kbps), EDGE (40-230 kbps) and UMTS (384 kbps and up)

GSM also uses a SIM card, so it's easy to switch your cell phone number and your contacts between phones (cntacts can be saved in the SIM card). Yes, I have a GSM phone, but it is not why I list up more good features for this technique.

And speaking of phones, I have heard that GSM phones usually have longer battery life than CDMA phones, and at least in the United States, the GSM carriers have a more varied selection of mobiles that are technically more advanced than CDMA handsets and have more high-end features as Bluetooth etc.

CDMA Facts

CDMA carriers have better coverage in the US, but most carriers in Europe use GSM. The CDMA technology is developed and licensed by Qualcomm. CDMA supports wireless data transfer to 153 kbps.

Nokia has CDMA cellphones, but they are fever than the GSM models. Also note that when it comes to software and phone features, Nokia´s CDMA handsets are not as technically advanced as the GSM handsets.

Here´s a complete list of Nokia GSM and CDMA devices: Forum Nokia Devices.

UMTS and 3G Data Transfer
Another issue, maybe not that important, to remember is how carriers are rolling out their third-generation (3G) data networks and services.