It's against federal law for a bill collector who works for a collection agency (as opposed to working in the collections department of the creditor itself) to call you at an unreasonable time. The law presumes that calls before 8 am or after 9 pm are unreasonable. But other hours may be unreasonable, too, such as daytime hours for a person who works nights. The federal Fair Debt Collection Practices Act (FDCPA, 15 U.S.C. § 1692 and following) bars collectors from calling you at work, harassing you, using abusive language, making false or misleading statements, adding unauthorized charges, and many other practices. Under the FDCPA, you can demand that the collection agency stop contacting you, except to tell you that collection efforts have ended or that the creditor or collection agency will sue you. You must put your request in writing.