You should be at the Help Desk as much as possible. To this end, if you need to ask somebody in another group (like Maintenance, or Engineering) a question use the phone to do so instead of going to their office. Using the phone will save both your time and theirs. It will also keep you more available for those coming to the Help Desk.
If you need to leave, be sure to lock your screen (see the section on Security in the Restricted Handbook for how to do this correctly). Either leave a message saying where you went, or when you'll be back (if you are leaving a message about when you'll be back, give a specific time instead of “Back in 5 minutes”).