From the contract:
3. Except when released to a Rest Period, a pilot awarded an “A” reserve Line must be contactable continuously twenty-four (24) hours a day, beginning at 0001 LBT of his first Reserve Day.
and
5. An “A” Reserve may not be required to report for a Trip Pairing or to begin a phone availability period less than nine (9) hours from the first attempt at contact by Crew Scheduling, or when he first becomes contactable on his first day of duty