Try the following code.

#!/usr/bin/perl

use warnings;
use strict;

use Archive::Tar;
use Data::Dumper;

my $cdr_dir="/root/prac/NSN_SGSN";

my @cdr_list=`ls $cdr_dir/*tar.gz`;
print Dumper \@cdr_list;

foreach my $file (@cdr_list)
{
        chomp $file;
        my $pipecmd = "tar -xvf $file";
        #open my $fh, q{<}, qq{tar xzOF $file | } or die $!;
        open(my $PIPEIN, '-|', $pipecmd) or die "Opening pipe [$pipecm
+d]: $!\n";
        while ( my $line = <$PIPEIN> )
        {
                print $line;
        }
        close $PIPEIN;
}
[download]

Try whatever the option you want with the tar command, I used -xvf for sample tesing.

You have included Archive::Tar why do not you use that module to read the tar file content ?