What is CDMA?
CDMA which stands for Code Division Multiple Access is primarily used in the U.S. and small regions of Asia. Each handset is tied to a particular network (such as Sprint or Verizon).
What is GSM?
GSM which stands for Global System for Mobile [communications] and is the world’s most widely used phone technology. Approximately 80% of the world uses GSM technology when making wireless calls, this equates to almost 3 billion people using the technology.
GSM has the advantage of using a SIM card which is tied to a particular network (such as T-Mobile or AT&T) rather than the handset being tied to the network. This allows users to move networks with their existing handset by swapping the SIM. Some handsets are ‘locked’ by the network on a post-pay contract, but can almost always be unlocked on request.
International Cell Phones
For practicality GSM offers the widest international roaming capabilities. GSM can be used in over 138 countries worldwide, compared to CDMA which can only be used in 2 countries worldwide. This makes GSM the perfect technology for traveling.
With CDMA the user would need to purchase a separate GSM European cell phone or international cell phone specifically for traveling as CDMA handsets work only in limited countries. With a GSM handset no additional purchase is necessary, it is possible to continue using it while roaming internationally in most countries. However, this can be expensive and a much cheaper alternative is local SIM card rental. Simply swap the U.S. SIM for an international SIM rental and a user can carry on using their handset as normal at greatly reduced call rates.