If it is a debt collector - a real one, not the foreign 3rd world kind, yes & no. If you don't return the call, or send a letter to them asking them to validate the debt, they can call, call, call. It can be as early as 7am, and as late as 9pm. It varies from State to State, Province to Province. There is a great deal of fraud going on to do with foreign criminals calling trying to extort money on debt's you do not have. Be cautious.