SIM300 GSM Modem/ Module can be used to send and receive SMS or make/receive voice calls. It can also be used in GPRS mode to connect to internet and do many applications for data logging and control.
In GPRS mode you can also connect to any remote FTP server and upload files for data logging.
This SIM300 modem can either be connected to PC serial port directly or to any microcontroller.(Arduino, 8051, AVR, ATMEGA, PIC)