Validating phone number in ruby

Question

What are the rules for validating a North American phone number? Also, is there a regex I can use? Is there a gem to do this?

Here are few rules I have

Answer 1

The rules I used in my perl code for validating NANP phone numbers came from an email sent by Doug Newell to the telnum-l mailing list, which I reproduce below, somewhat simplified to only consider full 10 digit numbers:

The number 10 digits long.  We'll call this pattern:
    ABC DEF XXXX

A may not be 0 or 1.

B may not be 9.

A+B may not be 37 or 96.

B+C may not be 11.

D may not be 0 or 1.

You may be able to extract a regex from libphonenumber's metadata, but beware, it is GNARLY AS HELL.