type some text for Eg.Motor On and send the message to GSM module
from microcntroller you read the message
AT+CMGF=1 <enter>
AT+ CMGD=1 //delete the 1st message
For new SMS, URC will be received
on the screen as +CMTI: SM ‘no’. //in this case 1
after that read the first message
AT+CMGR= 1<integer number where message is stored in Inbox>
check for Motor On text. if it is present then switch on the motor else dont.
Like this you can control many devices
Aamir