Mobile telephone. Date and time displayed on the LCD (liquid crystal display) screen interface on a mobile telephone. The screen is also the earpiece, with sound emerging from the speaker (holes above the screen). Mobile telephones often include PDA (personal digital assistant) software, such as a phonebook and a diary (paper version seen in the background). This function is combined with the communications function. Mobile telephones send and receive voice and text data as low-intensity microwaves. The phone keypad is partially seen at lower right. This model is manufactured by Samsung, and the mobile phone network operator is T-Mobile.