Another idea here is to do something along the lines of the following:

foreach my $line (@the_cell_site_lines) {
    my @data = split /\s+/, $line;

    # If you want the cellnumber, do the following...
    my $cell_number = $data[12];
    $cell_number = substr($cell_number, 2);

    # Do something here with the cellnumber you now have.
}
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Once that happens, I can grab the 13th item (remember that Perl array indices start at 0, so it's the 12th index). That item is "x'503E". I have to get rid of the first 2 characters, so I use substr. I could've used a regex (something like $cell_number =~ s/^x'//;), but why use a cannon when all you need is a pistol? substr is faster and clearer.

Creating a hash of cellnumber => cellname is an extremely good idea, and I suggest you do that. There are ways of putting that into a separate file and bringing it in either using do or require. If you want help with those, ask. (Oh - when you first do your testing, don't type the entire hash in - just use maybe 5-10 entries, to make sure your code works. Then, add the rest.)

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/me wants to be the brightest bulb in the chandelier!