Based on a 2015 National Labor Relations Board (NLRB) ruling, office manuals or handbooks can't have overly broad prohibitions on employee use of cell phones. Besides which, if you feel you can't treat your staff like adults, that's a bigger problem.
That being said, there is nothing wrong with issuing a simple and sane cell phone policy just as you might do for a dress code, calling in sick, vacations, PTO, etc. If you feel you need a cell phone policy here is my recommendation:
Cell phone use (including texting, checking Facebook, etc.) should only occur during breaks or meal periods and never in front of patients as it can give patients the impression they are not important. It can also cause you to be distracted causing inaccurate documentation, incorrect data entry, etc.
TEXTING PRACTICE OWNER OR OFFICE MANAGER
Staff are prohibited from texting the dentist or office manager for any reason including “texting in sick”. This also removes any potential violation of a patient’s privacy.
The office phones are our main means of scheduling patients and conducting business. Therefore, we ask that you not use the office phones for personal use except to receive an emergency call from a family member, etc.
OFFICE COMPUTER USE
Office computers are never to be used for personal use. Period. The reasons for this are obvious including the possibility of infecting the office computer system with a virus. Doing so can result in immediate termination
Note: Our office computers are set up with software to monitor all Internet activity. E-mail messages and other use of office computers is not confidential, and even though you may be issued a private password or other private access code to log in to the computer, you should have no expectation of privacy with regard to your use of the system.