#!/usr/bin/perl -w
use strict;
local $/;
my $line = <DATA>;
if($line=~m/(\d+):\s+From:\s+(.*?)(?=Length)/s){
    print $1 . $2;
}

1;

__DATA__
There is a new voicemail in mailbox 11234567890:

    From:     "Unknown" <Unknown>
    Length:     0:13 seconds
    Date:     Thursday, January 19, 2006 at 11:35:01 AM


##</code><code>##

perl hate.pl
11234567890"Unknown" <Unknown>