Direct Inward Dialing is a feature that provides phone users with a personal ten-digit phone number, in addition to their internal PBX lines or extensions. DID numbers, like otherTelebroad services, are configured in the cloud and work without your company having to invest in dedicated physical phone lines. The feature offers an economical choice for multiple phone numbers and makes it easy for clients to contact employees directly without having to go through an IVR or a dial-by-name directory.
DID numbers are defined in the Admin Center by going to the general settings of phone numbers and selecting the user to whom the number is assigned. The number will then appear and can be edited under the Direct Phone Numbers list on the user's page. See more information and configuratation insturctions here.