According to the Department of Labor (DOL), an employee who is required to remain on call on the employer's premises and is therefore deemed to be "working" on call. An employee who is required to remain on call at home or who is allowed to leave a message where he/she can be reached is not working (in most cases) while on call. However, additional constraints on the employee's freedom could require this time to be compensated.

The terms "working" and "not working" are synonymous with "eligible to be compensated" and "not eligible to be compensated." Therefore, the location of the employee while on call (i.e., whether he or she is on work premises or at home) is the main consideration that goes into whether compensation can be expected. However, this is not the only consideration.

The issue of what constitutes an additional constraint on an employee's freedom is also a critical consideration. If an employee is able to "engage in personal activities" while on call away from premises, the on-call time will likely not be compensated. If, on the other hand, an employee receives so many calls that he or she cannot "finish a meal, read a story to his or her child or read a newspaper," then there is a good chance the employee will need to be compensated for his or her on-call responsibilities.

Disagreements as to whether an employee is "on call" can result in wage and hour liability claims.