Employers are monitoring their company cell phones at an increased rate due to the security and liability risks involved with using any company property.  Consider the implications of what would happen if an employee were to get caught texting or sexting a minor.  Now consider the productivity loss of a staff member using the mobile phone using the phone for unrelated business conversations and texts at the times when they are supposed to be working.  It may be time to start monitoring cell phone use a bit more closely.