Real Nerds have a Favourite V.90 / V.92 Modem Digital Impairment Learning Sound

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Uploaded by: thefakevip

Upload date: 11/17/2024

Description:

From the invention of modems up until the V.34 standard (28.8kbps to 33.6kbps), nothing more than an analogue phone line between two modems was necessary for achieving communications. But starting with V.90 (the first official ITU 56k standard, predated only by unofficial, manufacturer developed standards such as X2 and K56 Flex), in order to achieve the higher download speeds, ISPs had to make use of digital ISDN phone lines, and special digital modems.
The telephone network has been digitally switched in many areas since at least the 1980s, and the compression methods used in such switching systems limits the theoretical maximum data rate of any modem conversation, so eliminating one of the two conversion steps of a normal analog -> digital -> analogue phone call by using a digital modem on the ISP (or BBS) side allowed for the faster 56k speeds.
To determine what kind of conditions they're dealing with in order to try to handshake 56k download,, V.90 and V.92 modems perform a procedure known as "Digital Impairment Learning". In layman's terms, the originating modem (the one in your PC), sends a request to the receiving digital modem (at your ISP), asking it to make a particular noise. The originating modem then listens to this noise to figure out what data, if any, is being clobbered by digital compression on the line, and to negotiate around these impairments, to establish a stable connection, at the cost, of course, of speed. Upload speeds are not affected by any of this, because your originating modem is on a normal analogue PSTN line (telephone modems never went above 33.6k upload to my knowledge).
Because the originating modem is free to choose what sound is played during DIL, different manufacturers used different sounds, and so they can be used to identify what type of modem someone used to make a connection. An upstanding citizen of the internet has graciously archived many of these, for your listening pleasure: https://goughlui.com/2016/05/03/project-the-definitive-collection-of-v-90v-92-modem-sounds/
This sound is a handshake from an Agere softmodem, and is my favourite DIL of the bunch. If you're crazy enough to have read this entire post, comment below which one is your favourite!

I know there are some telephony nerds here which is why I posted this. I learned basically all of this from the various modem videos made by @themaritimegirl on YouTube, particularly this insanely long Modem test extravaganza! https://www.youtube.com/watch?v=iJZykOzULvc&pp=ygUedGhlbWFyaXRpbWVnaXJsIHRlc3RpbmcgbW9kZW1z

not considering myself a nerd, but found it very interesting. 
Speaking of telephone related stuff, thisisarecording.com is still down which makes me sad, so much good stuff was there and I didn't archive it in time.

Ah this one brings back memories!