I use http://www.snapanumber.com and according to their website it works with outlook. It's not a softphone though it can work with one. I click a number on a website or type it into the box and it calls my desk phone, when I pickup it dials the outbound number that I clicked. There's a free and a pro version.
To quote their website and a TAUG member, "Snap delivers one of the most significant improvements I have ever seen in the way I make calls. With it's intuitive interface, simplicity, and built-in intelligence, all of my phone calls are now just a click away. I'm in love with Snap, and can't imagine how I got along without it!" -- Jim Van Meggelen - Asterisk: The Future of Telephony Blaine Aldridge
