Can an employer require use of personal cell phone without compensation?

I've work for the company for 2 years now. I am a supervisor now. The company does medical billing and now are required to do a two step verification process to log into system. The company is now requiring myself and employees to use person cell phone for this process. They are offer wifi to keep from using cellular data. Myself as well as several employees have been told we will lose our jobs if we do not use our personal cell phones for this process. I would use the WiFi but then the company would have access to everything in my personal phone.