I am not sure why you mentioned telnet here, but any way, your code just works fine. I tested it with this client:

use IO::Socket::INET;

use strict;

my $socket = new IO::Socket::INET(Proto => "tcp", PeerAddr => "localho
+st", PeerPort => 1337);
while (1) {
    print $socket "1234\n";
    my $msg = <$socket>;
    print $msg;
    sleep(5);
}
[download]

Your server can write to my client with no problem. Whatever I keyed in to STDIN on your server side, was printed on screen on my client side.