In the 1950s through the early 1960s, residential consumers in NYC were offered two plans:
a) a true flat rate service, but this only applied to calls in your very local neighborhood.
So if you were calling the drugstore 1/2 mile away you were probably in the zone, but calling the movie theater three miles down the blvd to get its schedule cost you per minute.
b) An untimed, but charged per call, rate, that covered a reasonably decent area.
When this was first set up (at least in the early 1960s, can't say for earlier) you had an allowance of 75 "message units" in your base charge. Above those 75 calls you paid an additional 5 cents or so, untimed.
Note that the untimed message unit did NOT give you the entire five boroughs, It let you call your own borough and, depending on your location, about half the rest of the city and some suburban areas. For most people and most calls (certainly not all) that was close enough.
Bit by bit the 75 message unit allowace got cut down, so nowadays there's nothing there there. On the slight plus side back in the 1970s the "local area" for untimed calls expanded to the entire city.
(Nowadays a bunch of very confusing options are available through Verizon and the various CLECS, cablecos, and other folk). --
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