Could this be related to party lines? https://en.m.wikipedia.org/wiki/Party_line_(telephony) https://en.m.wikipedia.org/wiki/Party_line_(telephony) This is sim

Could this be related to party lines? https://en.m.wikipedia.org/wiki/Party_line_(telephony) https://en.m.wikipedia.org/wiki/Party_line_(telephony) This is similar to the other answer regarding answering a different phone in the same house, but perhaps more necessary if sharing a line with neighbours. Distinctive ringtones may have made this phone line non-disconnection behaviour unnecessary though. I’ve never experienced a party line - but they sound ridiculous (and fun).