The question "Receiving empty data from GPRS module" was voted off-topic with the comment "Questions on the use of electronic devices are off-topic".
I totally disagree with this vote. This is a programming question re an embedded application. The members voting this question off-topic seem to be confusing using cell phones with the programming and interfacing of M2M (machine to machine) cell modems in an embedded application.
I am currently working with a PCB that has four radio modems (cell, Bluetooth, Bluetooth LE, and proprietary). It is very difficult to get them to work correctly some times. I have spent days communicating back and forth with the FAEs of the manufacturers of the modems.
I located and downloaded the "datasheet" describing the software interface for this modem. It is 250 pages long.
This question is no different than the dozens of other questions on this site re how to interface with some sort of peripheral connected to a microcontroller.