Cell phones. Reasons seem obvious and too numerous to mention but I miss dial tones and busy signals and trying to catch someone when they are at home and within hearing of their phone's ring; knowing that every call was a sort of invasion on their personal life and not to be taken lightly. Waiting out rainstorms in a phone booth with your girlfriend making prank phone calls and chatting with the operator. The time delay on long distance phone calls and crossed lines. Never knowing who was calling or who would answer the phone and their unique ways of answering the phone which was not a reaction to who they see on the caller ID but a familial trait learned and honed and immediately identifiable. Memorizing phone numbers and using the phone book. Browsing the phone book just to see what your city had to offer or browsing it in the hotel while on vacation to see what you might do. Judging and comparing cities by the size of their phone books. Sharing a phone and its place in the household. Getting prank calls instead of spam.
Caller ID. As implemented, it isn't fit for purpose. I'd want something real, enforced, regulated.
IMessage/whatsapp/telegram/signal/rcs should all be pure gui on XMPP and fully open protocol with trust anchor mutuality, so it's one namespace to talk to everyone.
I think this is like asking which limb we should amputate to cure the
patient of a virus. Either people will master technology or technology
will master us. That is the simple, clear choice before us.