What is DID and how does it work?

DID or direct inward dialing is the set up that works with a companies PBX Private Branch Exchange system. This system allows a phone in a group of phones to have its own extension and allows for direct calls to that line.

DID works like this, each phone in the PBX system may be assigned a seven-digit telephone number, and this will include a four or five digit extension number.

Instead of a phone call coming into one of many different phones, that much like a call center who has several phones set up with agents to take the calls. Then a call comes in to one of those phones that will then be answered randomly. The DID is a phone that is set up specifically to receive phone calls through a specific number.

This system was developed in order to be able to assign certain employees a direct line number, without requiring multiple phone lines. This is the way telephony traffic is more efficiently managed and delegated.

In order to have an active DID, it is required that you have certain equipment in place. This equipment is an ISDN or digital line. A range of numbers you can use, these are obtained through the telephone company. Finally you need DID capable equipment at your premises which consists of BRI, E1, or T1 cards or Gateways.

You can also use this type of system for a fax server. This would be instead of using the place at the end of the 234 000 line, fax modem cards, and computers with fax server software, then use the last three digits of a number to recognize the faxes recipient.

This allows multiple users to have their own fax numbers, even in the case of only one single fax machine.

The DID makes use of DID trunks. With which forward only the last three to five digits, of the phone number to the PBX, or to the router gateway.

For example:

Gas Enhance Inc. has phone numbers listed in the number ranges of 456-1000 to 456-1900. The caller into the business calls the number 456-1354. The local central office will then send the call to 354, to the PBX or the packet voice system.

The packet voice system or the PBX would then ring the extension line of 354. Using this process will make it possible to get the call through to the correct recipient.

In short, many companies ask their phone service company to allot them an area code, a three-digit prefix and a group of numbers that is specifically contacted with the said company. They will then set up this form of network using their PBX phone system to that outside callers can contact anyone in the company by dialing the unique designated phone number.

There is no limit on how many or few numbers a company is designated in the DID process. This means that a small company in addition to a large company can utilize this technology and convenience.

This also means that anyone inside of the company can dial another person in the company without having to dial the entire phone number, they only dial the extension number at the end of the seven digits. This is the four-digit number at the end.

The benefit of this DID or Direct Inward Dialing is that any person can call the extension, or phone number in order to connect to the recipient without having to go through switchboards and operators.

Therefore, this process looks more professional, is more convenient and makes better use of the telephony processes used.