nopein gprs

Nokia GPRS mobile supports 3 1 or 2 2 timeslot configuration (Multislot class 6). What does this mean and what kind of data transfer speed do I get?
The first digit indicates the number of downlink timeslots i.e. mobile is able to receive from the network. The second digit indicates the number of uplink timeslots i.e. how many timeslots mobile is able to transmit.

Nokia GPRS speeds are theoretically possible up to 64.2 kbit/sec under optimum network conditions. Nokia GPRS terminals support all four channel coding schemes specified in GPRS standard (9.05, 13.4, 15,6, 21.4 per timeslot). Top speeds are not yet possible with the current networks in place, and due to the packet switched nature, the typically achieved mean speeds vary between 15-25 kbit/sec. That makes mobile services comfortable to use. Multislot class 6 enables use of combinations up to 2 2, which is optimum for applications that need sending power e.g. email, and 3 1 for browsing and downloading. Current networks mainly support a maximum of 13.4kbit/sec per timeslot. When the user base grows in the cell, capacity is shared by network between each user. The network also takes care of error correction.

Why doesn't Nokia GPRS mobile support 4 downlink timeslots?
Increasing multislot capacity does not necessarily increase transfer speed since the network provides only best effort delivery and the network load probably limits usage of higher multislot classes, especially to downlink direction.

Ref. http://www.nokiame.com/tech-GPRS-starting.shtml