Not paranoid but know the rules. Do not answer the phone before 1800 and do not call them to acknowledge until after 1800. Trips can be acknowledged on CCS so there no need for contact at all in that case. As Dave said, a voice message is not an assignment, period. It's easy to feel we have to react to them but don't. It is safe to call at or after 1800.

20-K-7-d Assignments made after 1759 on the last day off prior to reserve days shall be placed in the Pilot's schedule and the Company shall notify the Pilot by phone. The assignment shall not require the Pilot to:
20-K-7-d-(1) depart prior to 1300, for a Trip; or
20-K-7-d-(2) begin earlier than 1200, for a Short Call assignment; or
20-K-7-d-(3) report prior to 1200, for a Field Standby assignment.

Many folks don't acknowledge last day off assignments at all which I don't advise. At midnight you go on long call and sometimes they see you haven't acknowledged and can now call at will. I had a 1600 SC that I did not acknowledge and they called at 3am to assign it, waking me up from a deep sleep. I'd rather go to bed knowing that I've acknowledged it and once acknowledged I'm released to the assignment and I can turn off the phone until the SC starts.