Hello Ravi sir.
I am using SIM800c module. Its taking basic AT commands but while I am sending GPRS related commands Its getting error. And also while sending a call command (ATD+mobile number) its showing me no “dial tone”. I am giving power to the module through Arduino uno board and connecting the powerkey to the ground through resistor. so is it a problem of powerkey or supply? and if u have any working circuit or schematic related to powerkey please give me the reference of it .
Thanks for support in adv,