Figure 10.10 Key UICC standards 10.6 User Interface The User Interface (UI) of the mobile devices creates the first impression for users' eyes and minds. User Interfaces play a crucial role in facilitating a pleasant and rich user friendly experience. UI allows customers to control their phones and transmit and receive information. UI at least consists of audio input (microphone) and output (speaker), display device, keypad, and an accessory connector to allow optional devices to be connected to the mobile phone [1]. The UI for emerging mobile devices also provides built-in cameras, MP3 players, video capture and play, Internet and email access, touch screens, sensors, additional buttons for text input and special functional keys, and slots for external memory. We also see personal organizer applications such as calendar, scheduler, notepad, alarm clock, and calculator in the majority of the phones. The Audio interface assembly consists of a speaker and microphone that allow customers to talk and listen on their wireless telephones. The Display assembly traditionally allows the customers to see dialed digits, caller ID, messages, and call status information such as radio signal strength. In phones dialed digits can also be changed before the call is initiated, a process known as pre-origination dialing. LCD (liquid crystal display) and LED (light emitting diode) are the two keys types of display that are used in wireless phones. The Keypad allows the users to dial phone numbers for calling, answer phone calls, type and send messages and also terminate calls, and SO on. It usually consists of 0-9 number keys, the * and # keys, volume keys, SEND, END, and SO on, keys. Some keys are used for multiple purposes namely to turn on the phone, the user may press and hold the END button. The Accessory Interface normally infrared or wireless, allows data port for connection to computer (Internet connectivity), external antenna connection, hands-free kit, and external power supply (such as cigarette lighter sockets in cars).