What is Direct Inward Dialing (DID)?

Direct inward dialing (DID) is a service that local telecommunications providers offer to business customers in which the businesses can lease a large block of numbers that go over a smaller set of physical phone lines.

For example, 100 phone numbers could be supported by just 8 phone lines. This allows an organization to assign unique phone numbers to all its staff without having to connect 100 physical phone lines to its PBX.

Previously, people calling into a business might dial a single phone number and then a switchboard operator would connect them to the person with whom they wanted to speak. Direct inward dialing (DID) eliminates this model by providing direct lines to their employees.

Direct inward dialing (DID) has a significant limitation, however. In the above scenario, if a company only has 8 physical phone lines they can only have 8 inbound phone calls happening at the same time. Callers 9 and up receive a busy signal. Because of this, direct inward dialing (DID) may have limited use in call centers. It's important to assess the pros and cons of direct inward dialing (DID) technology when making decisions about call center solutions.