Originally Posted by Check Essential

They might like it to be that way, but I don't think there's any contractual obligation to call them and tell them "I am still sick".
Its common for them to just put "SICK" on your schedule for a single trip duration or a single block of reserve on-call days.
Beyond that, I think they would like you to call them or they can call you if they want to check your status but I don't think you're under any obligations to report for duty until you've reported in well and that little "OK" appears on your schedule.