How many people in the NANP live in places that still have 7D dialing? [telecom]

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The recent debate about splits vs. overlays has made we wonder what
proportion of people in each NANP country live in places that still
allow local calls to be dialed without specifying an area
code. Resources such as http://www.lincmad.com/areacodemap.html
provide wonderful ways to see where non-overlay NPAs are located, but
does anyone have population figures broken down on an NPA-by-NPA
basis?

Actually, we do know the answer for most NPA countries: Jamaica and
the Dominican Republic are both completely overlaid, so presumably 100
percent of their populations must dial with 10D or 1+10D. Conversely,
none of the remaining island members of the NANP have more than one
NPA each, so they probably all still support 7D dialing. Canada is now
almost completely overlaid. As far as I can see, the only remaining
Canadian NPAs without a current or planned overlay are 807 in
northwestern Ontario and 867 spanning the three territories. Both of
those regions are sparsely populated, so close to 100 percent of
Canadians will live in non-7D areas by 2024 (by which time the
overlays planned for NPAs 506 and 709 will be active).

The leaves the US. There are plenty of overlays, but also lots of
remaining singleton area codes. There is no obvious pattern: some very
populous cities (e.g., Detroit and Jacksonville) remain un-overlaid,
along with predominantly rural or tiny single-NPA states such as
Alaska, Hawaii, Wyoming, Montana, both Dakotas, Delaware, Rhode
Island, Vermont, New Hampshire and Maine. Conversely, although most
major metropolitan areas now have overlays, there are also plenty of
rural overlay examples, such as western Kentucky, northern Wisconsin
and the entire states of Idaho and West Virginia. The driving factor
is when an older NPA happened to require relief; no geographic splits
have occurred in the past decade, meaning that all relief NPAs
introduced since then have been overlays. In the decade or so prior to
the last geographic split (575 splitting from New Mexico's 505 in
2007), many new area codes were introduced, and different state
preferences dictated which form of relief (split or overlay) was
used. For instance, California's PUC was slower to embrace overlays
than many other states, which is why there are still so many singleton
NPAs (some of them geographically quite tiny) in the Golden State.

So can anyone hazard an estimate about what fraction of the US
population still has the ability to dial 7D calls?

Bob Goudreau
Cary, NC (in the 919/984 overlay)

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