Post #2027493

2025-09-17 19:24 UTC

@Theresacityinmymind I’m curious as to whether there was specific telecom kit that radio stations used to manage calls in the 70s and 80s - maybe if there was a bit of kit it used the same concept to work as the party line concept in the US, but on purpose? I understand the UK switched from US style phone networks to their less phreakable system (System X - https://en.wikipedia.org/wiki/System_X_(telephony) ) by the early 80s - a black box would work on UK networks up until that switchover.

Replies (2)

@dualkei@hachyderm.io 2025-09-17 21:45

@leymoo @Theresacityinmymind The UK switchover from analogue strowger to System X (& System Y), took a very long time, most of the 80s and into the 90s before it was completed. It did however leapfrog the crossbar systems used in other countries, going straight from electro-mechanical to digital. I do recall various UK universities and employers I was at in the early 80s having fully digital PABX systems ahead of the PSTN going digital. It's possible but unlikely the chat room was a PABX digital conference bridge, but I suspect the analogue theory is more plausible.

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@dec23k@mastodon.ie 2025-09-18 16:50

@leymoo @Theresacityinmymind There were many purpose-built phone line patch units; you would need to isolate the studio mixer from the telco -48v and avoid hum. A transformer (and not much more) could do the job. Telco certified ones were expensive, even for a single line. Even today: https://www.bhphotovideo.com/c/buy/Telephone-Audio-Interfaces/ci/8815

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