Difference is, you can transfer a Google number. And the information is held by a third party, not solely by you - it provides additional oversight and transparency.

Don't give kids your personal number. It takes literally moments to set up a Google Voice number linked to a cell phone that you can distribute - and then DEACTIVATE at the end of a trip.

And whether or not you can "always get the phone records to prove it" .. let's see how long a career lasts with even a single ACCUSATION, let alone conviction, of "inappropriate conduct with a student" on the record. Especially since I guarantee it would make local papers within a day, and those records would be available online *forever* when the name is Googled by a potential employer.