pkgmgr /iu:"TelnetClient"

Wait a bit for the install to finish.
I do wish that pkgmgr would actually wait until the install has finished before coming back to a dos prompt as it’s annoying that you have no idea when the install has actually completed. On my machine it takes about 30 seconds.
I’m finding it hard to believe that my laptop did not have telnet on it – as I use it all the time. However whenever I install telnet from the dos prompt I always have to look up the syntax (and it’s still quicker than going into add/remove programs.
Hopefully this blog post will hit the search engines and therefore the syntax will be displayed on the first page rather than having to open a Microsoft page, scroll down and then view the syntax.