>>Being able to telnet into a host requires that a telnet server be running on it.
>
>I don't think that's necessarily true. There only needs to be some service listening to the particular port. I've talked to devices (some had a command-line style interface through a specific port for configuration). I've talked to web servers via telnet client. I've talked to mail servers via telnet client.

OK, if you're using telnet in pseudo-raw TCP mode yes, you can talk to some types of other services.

Still, it might be worth it for the OP to check if there is any other service listening on port 1433. Particularly if there are multiple instances of SQL Server on the host in question.