CDMA Question:

Data Transfer Speed:

CDMA is faster than GSM.
CDMA2000 downstream rate is 2 megabits / second, through EVDO, where GSM downstream rate is up to 384 kilobits / second, through EDGE technology

Subscriber Identity Module (SIM) cards:

SIM is tied to the network, rather than the actual phone. Phones with card-enabled can be used with any carrier of GSM
Proprietary handsets are linked to one carrier only and not card-enabled in CDMA

Roaming:

GSM carriers have wider coverage of more rural areas, where as CDMA may not cover rural areas compared to GSM carriers

International Roaming:

GSM has facility to offer more international roaming, as the number of connections in world market dominate GSM network.
CDMA phones do not have the capacity; however, there are more countries that use CDMA networks.