His probation would normally continue until he is formally discharged from probation. If for some reason no hearing is held to discharge him from probation, and he appears to be on probation past the end of what should be his discharge date, he or his lawyer can investigate the status of his case with the court and take appropriate steps to ensure that he is in fact discharged. I don't expect that to be necessary.
He should not assume that he is free to violate any term of his probation until he is formally discharged.
If he expects his probation to end as of the 4th, and has a scheduled call-in on the 4th, it's quite clear that his probation will not end prior to that date. He can also ask his probation officer about the status of the discharge, and whether any additional assessments are due, at that time. I assume, as we're now talking "yesterday", he did exactly that - what happened?

