note
seattlejohn
For the obsessively curious, there's a lot of interesting (and apparently authoritative) information about U.S. and Canadian phone-number standards at <a href="http://www.nanpa.com">NANPA</a>, the North American Numbering Plan Adminstration. It covers arcana such as the so-called N11 numbers (911, 411, etc.), potentially valid area codes (<tt>/[2-9][0-8][0-9]/</tt>, except <tt>/\d11/</tt>, <tt>/37\d/</tt>, and <tt>/96\d/</tt>), vertical services codes (<tt>112?\d\d</tt> or <tt>\*2?\d\d</tt>), and so on. It even alludes to what will happen when North America eventually moves to 11-digit phone numbers (i.e., 4-digit area codes). Now there's a scary thought for anyone who's been writing phone-number validation code that assumes a 3-3-4 format.
<p> <font color="#666666">$perlmonks{seattlejohn} = '<a href="http://www.clyman.com">John Clyman</a>';</font>
251480
251572