prompter: Why do old dial-up modems make weird sounds when connecting to the Internet?

assistant: Old dial-up modems make weird sounds when connecting to the Internet because of the way they transmit data over the telephone line.

When a user dials a phone number to connect to the Internet, the modem sends a series of tones over the line to establish a connection with the remote modem on the other end. These tones are actually a form of digital data that the modems use to negotiate the terms of the connection, such as the speed and error correction methods to be used.

The sounds that you hear when a dial-up modem is connecting are the actual tones being transmitted over the telephone line. Specifically, the modem is sending a sequence of audio tones at different frequencies and durations that represent the digital data being exchanged. These sounds are often described as a series of beeps, screeches, and static-like noises, which can be quite loud and annoying.

The reason for these sounds is that the modem is essentially translating digital data into an analog signal that can be transmitted over the telephone line. Because the data is being transmitted over a voice line, the modem has to use audio tones to convey the digital information.

With the advent of broadband Internet, dial-up modems have largely become obsolete, and the strange sounds they produce are no longer heard as frequently. However, for those who remember the days of dial-up, the sound of a modem connecting can be a nostalgic reminder of the early days of the Internet.

prompter: You mention in the 2nd paragraph error correction, what is error correction?

assistant: Error correction refers to the process of detecting and correcting errors during the transmission of data.  The most recent protocol appears to be the ITU (International Telecommunication Union) V.42 protocol included in most dialup modems.

It uses Link Access Procedure for Modems (LAPM), where the remote modem detects errors through cyclic redundancy checking (CRC) and requests re-transmission of corrupted data (ARQ).

It is important to note that this process takes place at the Level 2 or Data Link layer in the OSI model.

assistant: Old dial-up modems make weird sounds when connecting to the internet because they use a technology called frequency-shift keying (FSK) to transmit data over a telephone line. When a modem dials a number and connects to another modem, it first establishes a handshake protocol to negotiate the connection parameters. During this process, the modem sends a series of audible tones, which are the strange sounds that we hear.

The modem generates these tones by converting digital data into analog signals that can be transmitted over the phone line. The sounds are created by two different frequencies, known as the mark and space tones, which are modulated to represent the binary digits 1 and 0.

The sounds we hear are a combination of the two frequencies and their harmonics, resulting in a unique sound pattern that is specific to each modem. This sound is also known as the "modem handshake" or "modem song."

The reason for the strange sounds is that the modem is sending and receiving data in real-time, and the sounds are an audible representation of the data being transmitted over the phone line. As data is sent and received, the sounds change in frequency and tone, creating the distinctive sound that we associate with dial-up modems.

prompter: Why do internet modems not make weird sounds anymore if they did back in the day?

assistant: Nowadays, most internet connections use broadband technology, such as cable or fiber, which do not require a modem to convert digital signals into analog signals. Instead, the signals are transmitted digitally over the network. As a result, the modem does not need to make any sounds to establish a connection, and the connection can be established much faster than with dial-up technology.

assistant: Because the conventional telephone network those old dial-up modems used was never intended to transmit binary data, with a maximum speed of 56 kbps, and we got better replacements. Therefore there is no need to install speakers in modems to check if the dialling is working, and the signals can no longer be heard with a phone.

- DSL (Digital Subscriber Line)

As an older internet connection, DSL still uses telephone lines, but it no longer dials a phone number or transmits with audio signals. The signals of DSL are in frequencies not used by phones, so they cannot be heard.

- Cable and Fibre

These connections don't use the phone lines, and the signals can't be heard.

assistant: While later iterations of old modems used ultrasonic portions of the spectrum for their communication rather than the region of sound we can here, the reason modern modems don't make noise is that the copper connection to the "cabinet" is not longer a phone line but another digital data over copper connection. In addition, many buildings now have "Fibre To The Premisis" or FTTP, meaning no copper is involved from the Router to the ISP.

assistant: Old dial-up modems make weird sounds when connecting to the internet because they are performing a "handshake" process to test the telephone line quality. During this process, the two modems send precisely specified sounds and listen to what is heard on the other end. This allows them to negotiate settings such as speed and compression methods. The noises are also used to transfer data in an analog format, which was common during the early home PC era of the 1970s and '80s. 

So basically, old dial-up modems make weird sounds when connecting to the internet because they are testing the telephone line quality and exchanging signals with each other in a process known as handshaking. The modem sends precisely specified sounds and the other listens to see what it actually hears on the other end. This noise was the analog world's way of transferring data.

prompter: How does this relate to the history of Phreaking?  Also, how might I make music using old modems?  I have seen great projects of this kind by Sam Battle, on his YouTube channel Look Mum No Computer.  Does anyone collect old computer hardware for a museum anywhere in the USA?

assistant: Phreaking, which is short for phone phreaking, is the practice of exploring and exploiting weaknesses in the phone network, usually for the purpose of making free long-distance calls. The origins of phreaking can be traced back to the early days of the phone network when it was operated by AT&T and relied on analog signaling.

The strange sounds produced by dial-up modems were also a target for phreakers who found ways to manipulate them for their own purposes. One famous example of this is the "blue box" which was a device that could mimic the sounds produced by the phone network to allow phreakers to make free long-distance calls.

Regarding making music using old modems, it is possible to create interesting sounds by manipulating the sounds produced during the handshake process. By recording and layering different modem sounds, it is possible to create unique compositions. There are several online tutorials and resources available on this topic, including the work of Sam Battle that you mentioned.

As for collecting old computer hardware for a museum, there are several organizations and museums in the USA that specialize in preserving and displaying vintage computers and technology. One example is the Computer History Museum in Mountain View, California, which has an extensive collection of historical hardware and software on display. Other organizations, such as Vintage Computer Federation and The Living Computer Museum, also collect and exhibit vintage computer hardware.