I want to manipulate files that are present on another server.

I tried telnet. I get the following error:
Connection to <hostname> closed by foreign host.

I need to do this through a KSH. Any help is appreciated!

Thanks,
Edison

That means you are not allowed to telnet to that server.
Have you tried to ssh to it?

I have not tried ssh. Do we need anything installed on the UNIX server in order to be able to SSH?

Yes, an ssh daemon like openssl's sshd. This is very, very common however, I would be suprised if a UNIX server didn't have something like that installed, even if maybe disabled. Just try logging in with ssh and see if it works, it easily could.

Could you please give me a command?

Since I am running a script i do not want the remote server to prompt for a password.

If you don't want ssh to prompt for a password then you should setup keys between the client and the server. A quick Google search should give you all the information you require to set this up.

The command is simply ssh. It is used like: If you omit any command to be executed, you get an interactive shell.

Like Lazydog says, logging in without a password is something you must set up in advance. This involves generating a public/private key pair and placing it on the server so the server and client can recognize each other. Once this is done, you will be able to run the command without any special parameters and login without a password. Hunt for ~/.ssh/authorized_keys in ssh's manpage.