It would be inappropriate to let Monday's sunset pass by: The early analog phone system, the 1G (first generation) that defined what followed, is shutting down. AT&T and Verizon will turn off their networks on Monday, and AT&T will shut down its original digital network that used TDMA. The big problem here isn't cell users, which the cell companies track directly, and which have been getting outreach for some time to get swapped off analog-only phones. Rather, it's alarm and automotive users.
This issue was overlooked until a few years ago, when an industry group took a survey, discovered 1m of 30m monitored alarm systems used analog cell connections (850,000 of those just as a backup, in the very real case when a phone line was cut). As of six months ago, the number is believed to be under 400,000. Smaller alarm system operators are probably the root here, where they haven't aggressively upgraded their customers. (Customers might not want to pay several hundreds and higher recurring monthly fees, either, but the alternative is nothing.)
GM had about 500,000 of its 5m customers using analog services with OnStar, and shut down the analog offering on January 1. There's a lawsuit underway about the failure to offer an upgrade.