Disclosed is method for searching for a telephone number and performing a function using the detected telephone number on a mobile terminal, which includes checking whether an input by a user in a standby mode is a number of consecutive digits, searching a telephone number database (DB) in the mobile terminal to detect and display telephone numbers having the inputted number of consecutive digits, searching the telephone number DB when the input by the user is a character or characters to detect and display telephone numbers of people having names corresponding to the inputted character or characters, displaying a menu of functions available using any of the displayed telephone numbers. The user can input a keyword for a telephone number in an idle state of the mobile terminal; without the need to select a separate menu for telephone number search.