18. When a reserve pilot is given an assignment, his duty time will commence at the scheduled report time of the assignment, or when he actually reports, whichever is later. He will remain on duty until he is released to rest by Crew Scheduling or the later of:
a. The scheduled termination of his assigned reserve period, or his ready reserve assignment, which ever comes first.
b. The termination of an assignment which may extend beyond the scheduled termination of the reserve pilot's reserve period or the scheduled termination of his ready reserve assignment.
c. Limitations set forth in Section 12 or the applicable FARs

When you check out (from your RR....leave and do not answer the phone!!!)
They can call you before the end of your READY RESERVE for an assignment up to 1 hour after...but can't call you after you check out.