There is a lot you can do to make your code better, as shown below. Note that this will not make your code faster.

• Localize your variables (using my).
• Localize file handles too, after making them lexicals. (Now that they're scoped, close is no longer needed.)
• Use strict to make sure your variables are localized.
• Use warnings to detect errors.
• Don't open four files when you only need to open one or two.
• Indent properly.
• Use the safer 3-arg open.
• Don't hardcode the area codes.
• Don't use regexp to search for strings. Use index for a great speed boost.

use strict;
use warnings;

use File::Spec qw( );
use IO::Dir    qw( );

my $dir  = 'E:\\Documents and Settings\\ebrine';
my $cell = File::Spec->catfile($dir, 'Cell.txt');

my %area_codes = map { /(\d+)/; $1 => File::Spec->catfile($dir, $_) }
                 grep /^\d+\.txt\z/i,
                 IO::Dir->new($dir)->read();

my $num;


... Tk code ...

    
sub search {
   my $found = 0;
   my @number = split(/-/, $num);
   my $search_text = join '', @number;

   my $file = $area_codes{$num[0]};
   if (defined $file) {
      open(my $fh, '<', $file)
         or die("Unable to open file for areacode $num[0]: $!\n");

      $found = search_file($fh, $search_text);
   }

   if (not $found) {        
      open(my $fh, '<', $cell)
         or die("Unable to open file for cellphones: $!\n");

      $found = search_file($fh, $search_text);
   }

   ... Show results ...
}


sub search_file {
   my ($fh, $search_text) = @_;
   
   while (<$fh>) {
      return 1 if index($_, $search_text) >= 0;

      ... Update ticker ...
   }

   return;
}
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