USPS employees must be paid if they have to be available for quick response. These employees must be compensated accordingly. On-call payment is not interrupted when the employee is called back to work. During a callback, the employee is at work, paid normal pay, and continues to receive on-call pay.
Callback pay applies regardless of whether the employee has been placed on-call.
On-call and callback pay apply to all USPS employees and are contract provisions in all three collective bargaining contracts.