Part of MegaPhone, it lets you choose settings in the Telephone control panel to determine how it will interact with your U.S. Robotic Sportster modem. Some of the options that you might want to change include: which ringing sound MegaPhone plays when you have an incoming call; how many rings MegaPhone should wait before it answer a call and record the message; whether to enable MegaPhone's caller ID capability; whether MegaPhone will dial with Touch Tones or rotary telephone style pulses. The telephone setup control panel includes these options and several other. Unless you feel confident that you understand how the other options affect your telephone, you should not change these settings.