The old coin-operated public phones in Ireland (and probably the UK) - the ones with the A and B buttons - were hackable in this way for local calls. I haven't

The old coin-operated public phones in Ireland (and probably the UK) - the ones with the A and B buttons - were hackable in this way for local calls. I haven't found much on-line about how they worked, but here is a youtube video - https://www.youtube.com/watch?v=SS-tEun2XMc https://www.youtube.com/watch?v=SS-tEun2XMc Although this style of phone was from the 50s or 60s, they remained in use for decades in private settings like schools, hospitals, hotels, pubs and the like right into the 90s. I never paid for a local call from our high school phone by using this tapping technique. But thinking about it now, I suspect the calls weren't "free" - it just meant that the contents of the cash box was not enough to cover the bill the school received every month.