[PHP] Regex (Phone Number)

[Albert Padley]

I have been struggling with a javascript regex validation for U.S. 
phone numbers all afternoon. This is part of Manuel Lemos' Formsgen 
class. This is limited to the 7 digit number sans 3 digit area code. To 
be complete, the regex should disallow a phone number that begins with 
0 or 1, 555 or any digit followed by 11. Here is the regex I'm using:

^(?!\d[1]{2}|[5]{3})([2-9]\d{2})([-])\d{4}$
Manual Lemos indicated to me in an offline post that this should throw 
a javascript runtime error because of the (? at the beginning of the 
regex. I have tested it in over a dozen different browsers (Windows and 
Mac) and the only one that throws the runtime error is IE on the Mac. 
All others catch the errors I am trying to trap for with no runtime 
errors. Can this regex be improved on or do I have to live with the 
idiosyncratic behavior of Mac IE?

Thanks.
Albert Padley