US debt collector: what happens if I dispute the debt within 30 days?

CFPB says you generally have a 30-day validation period to dispute all or part of a debt. If you send a written dispute or verification request within that period, the collector must pause collection of the disputed amount until it provides verification. Official source: Consumer Financial Protection Bureau. Guide: https://getinstantlaw.com/debt-collection/debt-collector-contacting-me