FSBO's and lockboxes

[Account Closed]

I am listing my Tucson house on the MLS and on Realtors.com probably via Owners.com. It's close enough to me that if an agent is in the neighborhood and wants to show it, I can drive over to unlock the door.
I've been thinking of putting a lockbox on it, but how do I know if it's an agent that calls for the code, or some squatter?
I know the agencies are now sent a signal when someone accesses their boxes, and supplies the agent' s code. I'm not an agent, I don't have that ability.

How would you handle this?
thanks,
OFgift