In this paper I have talked about basic of GSM and GPRS and there networks and the network modeling, some fundamental GSM terminology is necessary to know it, The GSM/GPRS air interface, which can be assumed to be the bottleneck of the system, is a combined frequency division/time division system. A cell of the network is assigned a certain number of frequencies, GPRS is standardized to optimally support a wide range of applications ranging from very frequent transmissions of small data volumes to infrequent transmissions of medium to large data volumes.Since GPRS is packet oriented it enables volume based charging in contrast to GSM like charging of online time. This will open the door too a variety of new Internet applications, where you can stay constantly online while you pay only for the occasional data transfer.Network Architecture, after that I have mentioned the simulator of GPRS, Some detail relating to its technical features are given and the chapter concludes with a description of the process used to validate the simulator, GPRS complies with the standard Time Division Multiple Access (TDMA) scheme of GSM, i.e. the burst structure of GPRS is compatible to standard GSM. Nevertheless, there are many extensions made to better adapt to the needs of a packet oriented transmission, e.g. up-and downlink resources are used independently. A GPRS terminal is also allowed to operate in a multislot mode to improve the flexibility and to cover a wider range of Quality of Service requirements. And after that I talked about mobility management in GPRS and security, GPRS provides a security function similar to that of GSM. It is responsible for authentication and service request validation to prevent unauthorized service usage, also about GPRS service interactions and limitation of GPRS terminals may be constrained by the number of time slots they can handle. And the evolution of GPRS system is that GPRS is a stepping stone towards third generation wireless communications.