I work in a retail store, so we find lost phones all the time that don’t belong to colleagues. And I also don’t have company email.
FYI, Not everyone works in an office setting.
I think all my usual tricks have been listed (emergency ID, Siri, trying to send a photo to the cloud).
My store also has a bad cell signal, so if they aren’t on WiFi it’s hard too. At my store we keep lost and found 30 days. If it’s an iPhone, I try to charge it with my own cord for a few days to see if they get a call, or give them a shot to use Find my phone.
This is a good reminder to the rest of us to make their phones are easy to return if lost. Use Find My Phone and put an emergency contact in the health app at the very minimum, people!