In my first year of university I used dial-up to connect from home. The university had a mixture of 14.4Kbps and 28.8Kbps modems all tied into the same phone number, so it was random which kind you got. Obviously, doubling your data rate in those days was easily worth hanging up and trying again as many times as it took! The handshaking sound of the two types of modems the university was using were audibly distinct, so you could hang up and try your luck again immediately if you heard a 14.4K modem handshake. Listening was much quicker than waiting for the handshake to finish and then testing the download rate.
So, why did a 14.4Kbps modem handshake sound different from a 28.8Kbps modem handshake? The scrambled data test phase seems to be a likely culprit, because modems with different capabilities should sound different in this phase. There are plenty of 14.4Kbps modem recordings on youtube, but I couldn't find a 28.8Kbps handshake recording to do a proper comparison! It might also be that different brands or models of modems could be distinguished from one another before they even got to the scrambled data test.
In my first year of university I used dial-up to connect from home. The university had a mixture of 14.4Kbps and 28.8Kbps modems all tied into the same phone number, so it was random which kind you got. Obviously, doubling your data rate in those days was easily worth hanging up and trying again as many times as it took! The handshaking sound of the two types of modems the university was using were audibly distinct, so you could hang up and try your luck again immediately if you heard a 14.4K modem handshake. Listening was much quicker than waiting for the handshake to finish and then testing the download rate.
So, why did a 14.4Kbps modem handshake sound different from a 28.8Kbps modem handshake? The scrambled data test phase seems to be a likely culprit, because modems with different capabilities should sound different in this phase. There are plenty of 14.4Kbps modem recordings on youtube, but I couldn't find a 28.8Kbps handshake recording to do a proper comparison! It might also be that different brands or models of modems could be distinguished from one another before they even got to the scrambled data test.