#!/usr/bin/perl -w
use strict;

my %filehandles;

foreach ('call1','call2')
{
   open my $fh, '>>', $_ or die "can't open $_ for append $!";
   $filehandles{$_}=$fh;
}

# use call_id in the print to select the right filehandle to
# write to

my $call_id = "call1";
print {$filehandles{$call_id}} "to file1\n";
$call_id = "call2";
print {$filehandles{$call_id}} "to file2\n";