Back in the 1980's, the state-run
G.P.O. gave way to
British Telecom and the promise that soon we'd be able to buy phones and accessories, that simply plugged into a wall socket...
I took this as a green-light for building my own telephone accessories and designed a bell replacement, using a 555 timer. The first version was quite simple - just to prove the concept (though it did nothing of the sort!)
The 555 timer can easily run a loudspeaker at high volume, so I took the basic astable circuit and added a bit of my own magic to Pin 4. Feeding the incoming phone line through a full-wave rectifier and a zener diode, seemed to me to be a great way to detect the "Ring" signal.
What it actually did - and to this day, I don't quite understand how - was receive my
local BBC Radio station (medium wave AM). I'd somehow built a single IC, loudspeaker radio
I don't think even
Sir Clive Sinclair managed one of those
(A little knowledge is a dangerous thing!)