I think the first thing to do is check employment law in your respective area and company policy.
I keep a seperate work( company supplied) phone and personal phone. I do this for several reasons, some guys at work only have a company phone using it as a personal phone too( company has no issues)
Reason I feel to keep them seperate-
1- everything on the company phone is on the company server,photos,emails etc
2-In a work related issue( law suit,workplace accident) phones can be seized for investigations
3- The company owns the phone number so if you leave,get reassigned etc you no longer have that number
4- Once home and over the weekend phone is plugged on to charger and ignored unless on call but there are set times and compensation