In determining whether the time is spent predominantly for the employer's or the employee's benefit, the key is how restricted the employee's activities are. No single factor determines the outcome. Instead, the courts look to a variety of factors in determining whether the on-call time is spent predominantly for the employer or the employee's benefit. Some of those factors are: (1) terms of the employment agreement, if any; (2) physical restrictions placed on an employee while on call; (3) maximum period of time allowed by the employer between the time the employee was called and the time he or she reports back to work (response time); (4) percentage of calls expected to be returned by the on-call employee; (5) frequency of actual calls during on-call periods; (6) actual uses of the on-call time by the employee; and (7) disciplinary action, if any taken by the employer against employees who fail to answer calls. FAIR LABOR STANDARDS HANDBOOK FOR PUBLIC EMPLOYERS, par. 420 (Thompson Publishing Group, Inc.).