From Aldensoft Software:
CiDial will automatically redial a specified Dial-Up Networking connection until your computer is connected to the Internet then monitor the connection and automatically reconnect if the connection is lost. CiDial can be used instead of the standard Windows dialer, but installing and using CiDial does not affect your Windows installation or dialer. CiDial automates the process of connecting and staying connected to the Internet. With CiDial you will not have to press a 'Connect' or 'Reconnect' button if your ISP's phone line is busy or doesn't connect the first time, and when your ISP hangs up on you CiDial will reconnect. CiDial is free and does not display advertising banners.