Purchase company Cell phone or NOT?

I’m in a dilema at the company I work and I need to streamline our company/sales cell phones.

We reimburse money for all sales reps, and have even taken over ownership of 4 sales rep numbers and pay for their phones and service.

My question is:
1. Is it typical to make sales reps and other personnel to carry two phones (their personal phone and company provided phone) or to let them have their own and reimburse the service charges?

Thanks