gprs serial ppp ip tcp
Just wondering what kind of TCP/IP data you want to be.
The reason that asking is that, you can do this either with Ethernet or Modem (both traditional modem or GPRS modem).
For the ethernet one, you may need a MCU, connecting to a LAN controller, such as Realtek's RTL8019AS. And do the TCP/IP stack in software. A simply way is to use a hardware TCP/IP chipset, like WIZnet's W3100A.
The different between is that, for the LAN controller, you must do the TCP/IP/UDP in software way, such that it will consume much MCU resource, like the processing power, as well as the memory usage. For using an HW TCP/IP chip, you can use a slower MCU, or you can have much bandwidth to process the data.
In the modem solution, you just need to interface the MCU with a modem, then do the serial communication. For the fix-line modem, you will need to implement the TCP/IP plus the PPP protocol, which will spend some resource on both code size an memory usage. Fortunately, serial communication usually is slower than the LAN one, which a slower MCU is ok (like 8051).
It is also same to using Wireless Modem (GPRS modem). The different is only the setup procedure. You still need to do the PPP, TCP/IP ... Luckily there is GPRS modem that have embedded with TCP/IP Stack, which can make the life easier.