This GPRS/GSM Shield based on the SIMcomm SIM800F Quad-band 850/900/1800/1900MHz module that delivers GSM/GPRS 850/900/1800/1900MHz performance for voice, SMS, Data, and Fax in a small form factor and with low power consumption, it is the absolutely substitute/upgrade version of the SIM900 module, with the same AT Commands for controlling and upgrade signal performance.