Yes u r right. Most of the GSM modem available in the Indian market does nt offer packet data transfer. There r few international manufacturer’s ( Siemens, Falcom) whose GPRS modem directly offer’s internet connectivity but they r very costly. If such modem is available in Indian market do inform me.
Yes man. It does involve lot of study. For instance refer Rappoport or Vijay Garg ( Wireless Networks). There u’ll get good knowledge about GPRS data frame structure. If u could suggest any other source plz enlighten me.