There are three classes:

Class A

Class B

Class c

Class A

Can be connected to GPRS service and GSM service (voice,

SMS), using both at the same time. Such devices are known

to be available today.

Class B

Can be connected to GPRS service and GSM service (voice,

SMS), but using only one or the other at a given time.

During GSM service (voice call or SMS), GPRS service is

suspended, and then resumed automatically after the GSM

service (voice call or SMS) has concluded. Most GPRS mobile

devices are Class B.

Class C

Are connected to either GPRS service or GSM service (voice,

SMS). Must be switched manually between one or the other

service.