Why did the dial up modem noise sound the same every time? What was the purpose of those sounds as the connection was being made?

Question

I understand that modems used the telephone line to transmit and decode sound into data, but I don’t understand why that noise everyone remembers needed to happen. You didn’t hear sound when you were loading a web page even though sound was being decoded by you modem… what was the purpose for it on start-up?

Edit: Autocorrect typo

In: Technology

Answer 1

The sounds that you hear at the two modems discovering each other, and agreeing on the speed to communicate at. The calling modem tries at the highest speed it can go, then retries at slower and slower speeds until the both modems are happy with the speed and the sound quality.

The only reason you can hear the sounds are so you can tell if the connection working. You can tell if a human picked up the phone, or if the line was busy, or never picked up. You will recognize that and do something about it faster than waiting for the connection timeout.

Once the connection is established the speaker is turned off – the sound still continues on the phone.