System information

Pattern-matching examples
This pattern matches any seven-digit number, as long as the first digit is 2 or higher:
_NXXXXXX
The preceding pattern would be compatible with any North American Numbering Plan
local seven-digit number.
In areas with 10-digit dialing, that pattern would look like this:
_NXXNXXXXXX
Note that neither of these two patterns would handle long-distance calls. We’ll cover
those shortly.
The NANP and Toll Fraud
The North American Numbering Plan (NANP) is a shared telephone numbering
scheme used by 19 countries in North America and the Caribbean. All of these countries
share country code 1.
In the United States and Canada, telecom regulations are similar (and sensible) enough
that you can place a long-distance call to most numbers in country code 1 and expect
to pay a reasonable toll. However, many people don’t realize that 17 other countries,
many of which have very different telecom regulations, share the NANP. (More infor-
mation can be found at http://www.nanpa.com.)
One popular scam using the NANP tries to trick naïve North Americans into calling
expensive per-minute toll numbers in a Caribbean country; the callers believe that since
they dialed 1-NPA-NXX-XXXX to reach the number, they’ll be paying their standard
national long-distance rate for the call. Since the country in question may have regu-
lations that allow for this form of extortion, the caller is ultimately held responsible for
the call charges.
The only way to prevent this sort of activity is to block calls to certain area codes (809,
for example) and remove the restrictions only on an as-needed basis.
Let’s try another:
_1NXXNXXXXXX
This one will match the number 1, followed by an area code between 200 and 999, then
any seven-digit number. In the NANP calling area, you would use this pattern to match
any long-distance number.
†
† If you grew up in North America, you may believe that the 1 you dial before a long-distance call is “the long-
distance code.” This is incorrect. The number 1 is the international country code for NANP. Keep this in
mind if you send your phone number to someone in another country. The recipient may not know your
country code, and thus be unable to call you with just your area code and phone number. Your full phone
number with country code is +1 NPA NXX XXXX (where NPA is your area code)―e.g., [phone].
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