[Al Skierkiewicz]

Gary,
I would view a phone as a custom circuit/outboard processor/computing device using it's own embedded battery under the robot rules as they stand. All wireless would have to be shown to be disabled to pass inspection as well as only providing power to a peripheral through the USB connection. As with any computing device/custom circuit, it must be weighed with the robot and be securely fastened. Duct tape is not a fastener for those thinking of easy solutions.
Al