What Is VoIP DID?
DID (Direct Inward Dialing) is a telephone system feature that allows the system to connect incoming calls to specific extensions without operator or attendant involvement. This requires blocks of dedicated DID numbers and special trunks to receive the incoming calls and a customer telephone environment that will recognize the correct destination for each call.
VoIP (Voice over Internet Protocol) is a technology that carries telephone calls over digital facilities by using "Internet protocol," which is the set of rules for formatting and sending messages over the Internet or private digital communications lines.
Other People Are Reading
-
Before DID
-
Large and medium-sized companies typically used a PBX (Private Branch Exchange) as their telephone system for internal and external communications and they listed only one "main" number.
Calls to this number would be answered by a telephone attendant who operated the main answering switchboard or console for their PBX. The responsibility of the attendant (or attendants) was to connect your call to the proper telephone extension.
Manual PBXs
-
Initially all PBXs were manual. This meant that the attendant had to connect all calls---incoming, outgoing or station-to-station---while the extension user waited. A company with only a few hundred extensions might have two or three attendants working during their busiest times. The larger the company, the more attendants were needed, and the greater the expense.
-
Dial PBXs
-
However, the invention of automatic or dial PBXs allowed extension users to make their own calls to other extensions and to dial outward calls directly (usually by dialing "9"). These analog systems saved user time and company money as fewer attendants were needed.
Digital PBXs and DID
-
New digital PBXs were developed that could handle DID trunks and automatically direct the incoming calls to the proper extensions. Once incoming callers started using the DID numbers exclusively and in combination with voicemail, many companies no longer needed full-time attendants.
VoIP, DID and More
-
Toward the end of the 20th century, VoIP became possible and started evolving rapidly. As a computer-based technology, VoIP not only easily matches the features previously offered by digital PBXs (such as DID), VoIP combines voice and data networking, offers new or enhanced features and lower costs.
-
