I have noticed phones with a handset (like the one in the image) have a little cover that resembles something like a cold camera shoe under the bottom of the handset’s top speaker holder. Is there a use for it? It has a line bump in the middle, but it doesn’t go all the way from both sides, it leaves a gap. I have also seem some of them have extra space on the top of the cover, and some don’t.
In the 80s there was a way to cheat phone booths in Germany: With a small tool that had an adjustment screw you could position the hook switch to an exact position where the phone booth had already connected the line but did not yet power up the rest of the machinery (including coin counters)
You could then call arbitrary nunbers by pulse dialing using the hook switch (the rotary dial was still powered down)
Basically a EU pulse dial version of phreaking.
My father, who died this year, used this a lot too make “free” calls in the 80s.