Help with Tracking Pay Per Call Campaign on Bing.

[Musashi]

So today I ran my first Pay Per Call campaign using Bing and I'm bit confused on what to do as far as tracking goes. I do have a call tracker so from the landing to making a call is not the problem. I'm just lost as to tracking the search term/keyword that brought the user in from the ad to the landing page. I have Google Analytics setup with a click event using the "tel:" link but i'm lost as to what I should be looking