eli5: The “handshake” between dial-up modems and why it made those sounds

Question

eli5: The “handshake” between dial-up modems and why it made those sounds

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Answer 1

The dial up modems communicate over phone lines (hence dial up), and that sound is the data that they’re communicating (1s and 0s) They have to tell each other what they are capable of (speed, location in the network, etc) before any actual data can be exchanged. That’s what the handshake is for, and once it’s done, actual data can be transmitted.