About 20 years ago in almost any home, the sound of a dial-up modem was a familiar one.
The sound you hear is refered to as a handshake, and is the modem on your phone line calling the modem of your Internet Service Provider (ISP) for its own type of conversation. The modems will make a connection and begin telling each other what they are capable of in terms of compatible protocols as not all modems are the same. Once they have a game plan, a series of binary signals will be sent through the line to determine the quality of the line and attempt to reduce echo and other noise.
Finally, the modems have agreed on how to proceed, and the speaker goes silent, allowing you to access the glorious internet in complete silence, that is until someone picks up the telephone in another room and is greeted by an ear full of OUCH!
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