I'm planning to make a security system wherein I can connect any mobile phone. I've seen some connection diagrams of mobile phone, where do we connect the hardware USART of the PIC16F877 to the mobile phone, Mbus or Sbus? I have experience in interfacing the PIC to a GSM module, I was here wondering if anybody knows, is there a similarity in the AT commands of a GSM Module and a mobile phone? Does all phones support text mode? On last thing, I would really appreciate is somebody could provide me websites that give me additional help in this regard. Thanks!!!!!