The inspiration behind the wireless world came from the need to provide users with mobility and to offer an alternative to the limitations of wired mediums. As a result, there are various wireless mobile technologies like GSM, GPRS, WLAN, and Bluetooth available. The user interface and the size of mobile devices are one of the main concerns in the design of mobile devices. In this paper, we design a single-layered touch screen based user interface. Unlike conventional multi-layered user interface, a single-layered user interface will make the user interface more user-friendly with smaller size. The memory requirements can be further reduced by implementing it in low-level languages. After design and implementation of the user interface, we integrate the user interface with the hardware of mobile devices through serial port with the help of AT commands.