A telephone number searching system supporting an automatic telephone connection in which a telephone number is searched for through the internet and automatically dialed, and a method therefor. A web server is connected to a telephone number database for storing multiple predetermined telephone numbers. An information terminal is equipped with a web browser which is selectively connected to the web server for submitting a search request to receive a telephone number service and searching a telephone number from the telephone number database to display at least one searched telephone number. One number is selected by a user among the displayed telephone numbers and dialed automatically by a telephone plug-in to set up a communication channel through the telephone.