That jogs a memory... back in the mid-20th century when phones were actually connected directly electrically (via exchanges full of Strowger relays), at least for local calls not passing through amplifiers/boosters... well an old hand electrical engineer once described to me that amongst his hacker spirited community it was considered a good wheeze to suddenly switch the call to a high voltage generator of some sort (a Tesla coil?) and blow up the recipients handset's loudspeaker. I'm dubious about their account of how spectacular this could be (suspect the tale had become exaggerated with time). But I was also dubious other protections might not kick in... and as noted here https://www.britishtelephones.com/lightng.htm the BPO removed lightning protection and other fuses in the 60s and didn't reintroduce them until more voltage-sensitive semiconductor equipment became more common.