This AT commands. It use into program for SIM300CZ module.With this file, you can search all usefull commands. Module SIM300CZ is used in communication with mobilphone.It fix for student in research. Not only Module SIM300CZ but also SIM900 can use this commands.-This is AT commands. It use into program for SIM300CZ module.With this file, you can search all usefull commands. Module SIM300CZ is used in communication with mobilphone.It fix for student in research. Not only Module SIM300CZ but also SIM900 can use this commands.