Stephen Sprunk wrote:

(The FCC prohibits allocating separate area codes to mobile carriers,
claiming that would be "discriminatory", so their numbers come from the
same geographical area codes as land lines. This causes many problems
and, in the end, hurts consumers.)

Causes problems and hurts consumers? What the hell are you talking about here?

Because the original mobile carriers were all subsidiaries of the incumbent
land line telephone companies, they thought in land-line terms.

For billing purposes, traditionally, calls from land lines were rated on
time and distance. Initially, cell phone calls were rated on time, only,
within the home coverage area, and time and distance, if the call terminated
outside the home coverage area. If roaming was involved, there was a time
surcharge based on the handset being physically outside the home coverage
area, although that didn't necessarily change how the long distance part
of the charge was rated.

The distance part of the charge was based on the distance between origin
and destination rating points. For land lines, the geographic polygon
associated with the rating point is called the "exchange". (The term
"exchange" also applies to the central office building that houses the
switch, but that definition isn't relevant for billing purposes.)

Every cell phone was assigned a rating point artificially so distance
charges could be calculated. Distance applied to outbound calls from
the cell phone if long distance charges were involved, and to inbound
calls from land lines. The rating point wasn't necessarily assigned to
the cell phone subscriber for the subscriber's convenience nor proximity
to the address to which the bill was sent. The subscriber, of course,
could ask for a phone number assigned to the rating point he desired,
if he was aware of the situation.

As long as cell phones were artificially associated with a specific
rating point, it made no sense to assign them to unique area codes
that were also geographic. If cell phone calls never had distance-based
charges associated with them, inbound or outbound, only then would it
have made sense to assign non-geographic area codes to them.

Yes, non-geographic area code is an oxymoron, but that's the term.

Area code 917 was assigned to New York City in 1991, opened in 1992. The
original area code was 212. Brooklyn, Queen, and Staten Island were split
out from 212 into newly assigned 718 in 1984. Also in 1992, the Bronx
was reassigned from 212 to 718. 917 was an overlay of 212 and 718.

At first, 917 was assigned to cell phone service, only. This annoyed
cell phone subscribers, as those dialing from land lines had to dial
extra digits. FCC got involved and ruled that geographic area codes
unique to cell phone service could no longer be created, and in case
of overlays, the same dialing plan had to be in place for calls dialed
to the home area code and the overlay area code. Home area code dialing
means that the area code of the originating and terminating phone numbers
are the same; foreign area code dialing means the area codes of the two
numbers are different. By FCC rule, overlays therefore eliminated seven digit
home area code dialing.

917 wasn't cell phone only for long. Today, it's a general purpose area
code and does have land line prefixes in it. Also, the other New York City
area codes have cell phone prefixes in them. Some Manhattan cell phone
subscribers have 718 cell phone numbers, for instance. However, 212
itself has no cell phone prefixes, although local number portability rules
would allow former land line numbers to be transferred to a cell phone.

Stephen appears to be perpetuating the myth that cell phone services lead
to line number exhaustion and thus area code exhaustion. This isn't true.
Area codes are exhausted when prefixes are no longer available for assignment,
but even in a prefix opened decades ago, there are numerous unassigned
line numbers.

The trouble is that prefixes in geographic area codes were typically assigned
to a carrier and used to route calls originating on one network to a
foreign network.

Local number portability could have solved the problem since LNP areas
require a lookup of the entire phone number, not just area code and
prefix combination, to learn what network the call terminates on. FCC
imposed LNP. Taking the technology to its fullest utility, all carriers
desiring to serve a particular exchange, land line, or rating point, wireless,
should have been required to make line number assignments from the same
pool of line numbers and no prefix should be unique to any carrier or network.

But LNP by FCC rules is a half-assed solution that doesn't eliminate a
great deal of waste of numbering space.