Hi,
vijay.jay5,
1. yes, it is possible to send file using GPRS modem, these device connects to internet and you can do anything with it. Problem is, GPRS is one of the least reliable connection and too slow for many applications. so sending large file through GPRS is difficult in real life.
2. It's not necessary to be in the same network(service providers), you just need IP address/port of server/client.
sukrutsystem,
give more details, like your hardware/software setup and sequence of AT commands.