Good Morning, I am doing a project based on GSM interfacing. The controller which i am using is AT89s52. The project is working successfully up to some extent but sometimes when controller sends AT+CMGS command i.e. to send text message, MODEM retaliates the command with > character, but as soon as controller gets response from MODEM it is getting reset. And as MODEM doesn't get Ctrl+Z command it gets stuck and total system gets failure. I am not getting the way out. I am facing the same problem even if i replace the controller with ARM-7 processor(LPC2138).