I initially felt the requirement for employees to purchase cell phones and pay monthly service charges was illegal, however, I realized this requirement was more 'unfair' than technically illegal.
Undoubtedly, this policy will upset employees, make them question the legality of the new policy and might temporalily lower the general morale, but its simply a policy - not a rule supported or defended by a law or court case.
Other than wanting to know if the leadership team enacting this policy consulted their legal department, any specialty HR team and state/local laws prior to rolling it out, I'd want to know more about the specifics of the policy to elimate grey areas of ambiguity and potential loopholes: how would the 24/7 policy execute? Would there be defined breaks from this accessibilty? How would breaks vary from level to level - and how? Would the possibility for overtime need to be evaluated? Would this policy be stated to new hires while interveiwing - and would it potentially deter talent? Would there be other incentives to offset these expenses? Would these expenses potentially be offset by salary increases? Would every manager implement this policy evenly across all applicable functions? When would the policy be placed in writing and how quickly would it be dispersed among the company?
Personally, I've witnessed this exact policy enacted - the morale sunk, employees began to be more open to outside offers, but generally speaking, work was getting done.