I might have tried to generalize that even further, though you still have regional issues to worry about. I.e. this won't work for everyone: 
@FORMAT_PHONE = (
   '%d%d%d',                              # 911 
   '%d-%d%d%d',                           # 1-411
   '%d-%d%d%d%d',                         # 5-1212 ?
   '%d%d-%d%d%d%d',                       # 55-1212 ?
   '%d%d%d-%d%d%d%d',                     # 555-1212
   '%d-%d%d%d-%d%d%d%d',                  # 1-222-2345
   '%d%d%d-%d%d%d-%d%d%d',                # 212-114-151 ?
   '(%d%d%d) %d%d%d-%d%d%d%d',            # (800) 555-1212
   '+%d (%d%d%d) %d%d%d-%d%d%d%d',        # +1 (800) 555-1212
   '+%d%d (%d%d%d) %d%d%d-%d%d%d%d',      # +01 (800) 555-1212
   '+%d%d%d (%d%d%d) %d%d%d-%d%d%d%d',    # +011 (800) 555-1212
   '+%d%d%d %d (%d%d%d) %d%d%d-%d%d%d%d', # +011 1 (800) 555-1212
   '%d%d%d%d%d (%d%d%d) %d%d%d-%d%d%d%d', # 10321 (800) 555-1212
   '%d%d%d%d%d %d (%d%d%d) %d%d%d-%d%d%d%d',  # 10321 1 (800) 555-1212
   '%d%d%d%d-%d%d%d (%d%d%d) %d%d%d-%d%d%d%d', # 1010-220 (800) 555-12
+12
   '%d%d%d%d-%d%d%d %d (%d%d%d) %d%d%d-%d%d%d%d', # 1010-220 1 (800) 5
+55-1212
   # etc...
);

my %L2M;
@L2M{qw: Q Z   :} = 1;
@L2M{qw: A B C :} = 2;
@L2M{qw: D E F :} = 3;
@L2M{qw: G H I :} = 4;
@L2M{qw: J K L :} = 5;
@L2M{qw: M N O :} = 6;
@L2M{qw: P R S :} = 7;   # some define this as PQRS
@L2M{qw: T U V :} = 8;
@L2M{qw: W X Y :} = 9;   # some define this as WXYZ
   
sub format_phone {
   my $number = shift;
   $number =~ s/[a-zA-Z]/$L2M{uc($1)}/eg;
   $number =~ s/\D//g;       # maybe allow # and * later??

   if (defined($FORMAT_PHONE[length($number)-3])) {
      return sprintf($FORMAT_PHONE[length($number)-3], split(//, $numb
+er));
   }

   return;
}

[download]

In reply to Re: Answer: How do I break down a phone number and rebuild it? by Fastolfe
in thread How do I parse a telephone number? by mofo

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