As most people know, United charges an extra $25 fee per passenger when booking by phone (unless you book through the automated system). Since I was booking Star Alliance flights that were not available online, I had to call. I tried the automated system, but it kept getting confused, due to my complicated open jaw routing. So I talked to an agent, who reserved all my segments, and I was fully expecting to pay the extra fee. The agent even told me that I would be charged. However, since I wasn't 100% sure about my dates, I asked the agent to put my reservation on hold for 72 hours. I got my confirmation number, but I didn't book anything. A couple of days later I called back, and since I didn't need to make any changes to my reservation, I just provided my confirmation number to the automated system, and then booked the flights that way. Sure enough, there was no booking fee! Enjoy!