Here’s a way to do it.

You’ll need Skype installed, and some SkypeOut credit (which you only need to make a call to a real ‘phone, this won’t cost any money).

#!/bin/sh
osascript -l AppleScript -e "tell application \"Skype\" to get URL \"callto://+447967XXXXXX\""
sleep 30
killall -m "Skype"
exit 0

Save the above somewhere handy in your path as ringring, do chmod 755 ringring so you can execute it.

Now all you have to do to get your ‘phone to ring for 30 seconds is type ringring in the Terminal, or, to make it even easier, you can set up a Quicksilver trigger to run the command whenever you hit a key combination.

Mere words cannot express how happy this makes me!

Admittedly, wodging some Applescript inside a bash script, then killing Skype to stop it from connecting and wasting your money on a silent ansaphone message isn’t very pretty. But I’m not clever enough to work out how to make Skype hang up after a set interval with AppleScript, and this way works, so it’ll have to do.