38 U.S. Code § 7457 - On-call pay
The Secretary may pay an employee to whom this section applies pay at the rate provided in section 7453(h) of this title except for such time as the employee may be called back to work.
(b) This section applies to an employee who meets each of the following criteria:
(c) An employee who is eligible for on-call pay under subsection (a) and who was receiving standby premium pay pursuant to section 5545 of title 5 on May 20, 1988, shall, as long as such employee is employed in the same position and work unit and remains eligible for such standby pay, receive pay for any period of on-call duty at the rate equal to the greater of—
the rate of pay which such employee would receive if being paid the rate of standby pay pursuant to such section that such individual would be entitled to receive if such individual were not scheduled to be on call instead, or