[otrs] show all caller's tickets

How can I modify the system so that when an agent takes a phone call from a user and inputs that user's username or customer ID into a new phone ticket, OTRS will pull up all of that customer's tickets or history at the bottom of the screen? I thought it did so when I was evaluating OTRS, but now that I have an actual install that I'm going to roll-out, I can't seem to get it working again. Thanks. -Jeff