What Is Dialed Number Identification Service (DNIS)? 

A Dialed Number Identification Service (DNIS) is a telecommunication service offered by phone companies that helps businesses determine which telephone number a customer dialed to contact them. Contact centers or call centers use DNIS, particularly in interactive voice response (IVR) systems, to route calls to the appropriate department or employee. DNIS is especially useful for companies that use multiple toll-free numbers or that use multiple inbound lines.