Harris & Harris, Ltd. Debt Collection Complaint

Harris & Harris, Ltd. Debt collection department,

I do not know Cont'd attempts collect debt not owed Debt is not mine Maryland

I continually get robo calls with the message " Hello, this is Harris and Harris limited. We are debt collectors. Please call us at - - - our office is open Monday through Thursday from - To - Central standard time Friday from - To - Central standard time and Saturday - To - Central standard time. Thank you. '' I do not have any outstanding debts and the caller does not address me by name. This appears to be phishing scheme to capture my phone number for further harassment. How can these calls be stopped. I have been on the Do Not Call list for nearly ten years.