lee@tis.com (Theodore Lee) (12/27/89)
From time to time, including even fairly recently here in the
TELECOM Digest, people make observations about how large a toll-free
region they are located in, or about how much more fortunate somebody
else is in being in an especially large one. Those observations made
me wonder: has any ever attempted to determine the size of toll-free
regions and list the largest ones, much as lists of the largest cities
or SMSA's are done? It sounds like it might make an interesting paper
or project for a telecom course; it might even have practical value.
Note that the question is not as well-defined as it might first
appear: each of the terms in "toll-free region size" is ambiguous and
has several reasonable meanings. To simplify things a little, let us
start by defining "local call" as follows: exchange B is a local call
from exchange A if making that call using typical non-measured
residential service adds nothing to the bill. (In locations where
there is an optional higher level of service that I think I have seen
called "metropolitan" service or something like that, assume that the
residence is paying for that higher level of service, i.e., has chosen
the broadest "normal" service it can.)
"Toll-free region" then has at least three meaningful
definitions, one of which I'll call "compact toll-free region", the
second "local toll-free region," and the third, "extended toll-free
region:"
Compact toll-free region: Let R be a set of exchanges. R is a compact
toll-free region if and only if for all exchanges x and y that are
members of R y is a local call from x and for all exchanges z that are
not members of R, there exists at least one x in R such that either z
is not a local call from x or x is not a local call from z. In short,
a compact toll-free region is a set of exchanges such that any two
exchanges in the region are local calls from each other and that all
exchanges outside the region are non-local calls to or from at least
one exchange in the region. (I don't know if "local call" is always a
symmetric relation: are there cases where A is a local call from B but
B is not a local call from A?) Note that, in theory, different compact
toll-free regions can overlap.
Local toll-free region: for each exchange x, find the set of all
exchanges y such that y is a local call from x. Each such set is a
local toll-free region. This is probably what a person means when he
talks about the size of the toll-free region he is in, since, in short
it is the set of all exchanges *HE* can reach toll-free.
Extended toll-free region: Define the relation is-linkable-to as
follows -- given two exchanges x and y, x is-linkable-to y if either,
a) x is a local call from y,
b) y is a local call from x, or,
c) there exists an intermediate exchange z such that either x is a
local call from z or z is a local call from x and z is
linkable to y.
It can be seen that is-linkable-to is an equivalence relation over
the set of exchanges. The set of equivalence classes under that
relation define the set of extended toll-free regions. In short, two
exchanges are in the same extended toll-free region if an appropriate
sequence of all local calls could be used to pass a message, e.g.,
using uucp, between customers in the two exchanges, noting that if
"local call" is ever non-symmetric some of the calls may have to be
initiated by receivers rather than senders. (An obvious first
question here is: is there in fact more than one extended-toll-free
region, i.e., are there in fact at least two areas where you "can't
get there from here?")
The hypothetical term project then is: a) identify all the
compact, local, and extended toll free regions. b) rank the three
lists of regions by geographical area covered, number of telephone
numbers covered, and population covered.
Has anyone done any of this? Any ideas short of looking at every
telephone book in the country how someone would proceed? (I'm not
intending to carry out the project, only curious as to whether it
could even be done.)" Maynard <jay@splut.conmicro.com> (12/29/89)
I would submit the Houston metropolitan area as one of the largest
toll-free regions, both in population and in area...
The central zone and first and second-tier exchanges (what's the
difference between central and first/second-tier, anyway, in this
context?) make up a compact toll-free area, by the definition given:
all calls involving two phones in this area are local. This area is
bounded, very roughly, by a circle forty miles in diameter, and
includes most of the Houston SMSA.
The normal toll-free area for someone inside that circle is bounded by
a rough circle about 60-65 miles in diameter, and includes anything
that could remotely be considered a suburb of Houston, including Katy,
Richmond/Rosenberg, League City, Baytown, and Tomball, extending well
into Montgomery, Galveston, Waller, and Fort Bend counties. The normal
toll-free area for someone in the parts of this zone outside the
central 40-mile circle is that circle, and all exchanges adjacent to
the caller's exchange. (I was disappointed to discover that my
parents, who live in Tomball, are a long-distance call from me in
League City, even though we both have metro service.) The extended
toll-free area is the same as the local toll-free area for the central
zone. There is precious little territory in the 713 area code that
this does not include.
Jay Maynard, EMT-P, K5ZC, PP-ASEL | Never ascribe to malice that which can
jay@splut.conmicro.com (eieio)| adequately be explained by stupidity.
{attctc,bellcore}!texbell!splut!jay +----------------------------------------
Here come Democrats...here come Democrats...throwing money a-way..."John R. Levine" <johnl@esegue.segue.boston.ma.us> (12/30/89)
I don't know if this counts by whatever rules one wants to use for determining toll-free regions, but if you have a cellular phone in New York City or northern New Jersey, any call to 201, 212, 718, 516, much of 914, a little of 203, and soon to be 908 incurs no toll charge beyond the usual per minute air time charge. There appear to be cases where it's cheaper to make a cellular call than a regular one, e.g. from Toms River NJ at the southern tip of 201 to Montauk at the eastern end of 516, a distance of over 100 miles. This seems to be true of both the A and B carriers.