direct inward dialling

[vince walters]

Hi,

I am new to voip telephony. I read about direct inward dialling (DID) and i was totally confused. Do all the providers provide DID'S?
what is the advantage of using DID'S?

[Tony]

Yes I guess a lot of people get confused by DID but it is actually very straightforward. The term is only really relevant for businesses as I can't really think of a non-DID need for the home.

Basically a DID is just your phone number. It means if anyone dials that number it will go straight to your home. Where the confusion may be is that some businesses have only one or two DIDs but they actually have many phones in their office. What happens here is that they publish the DID as their main number as that is what people call to reach the people in the office. A receptionist or more commonly an IVR system will then direct your call to the correct extension. These extensions cannot be called DIRECTLY as they are not DIDs and as such the phone company knows nothing about them. So in summary, it is the DID that is important. The only reason not to get a DID for every phone is the cost.

Tony

[andyf]

The real advantage of Direct Inward Dialing (DID) for traditional telephone calls is that it allows a company to have fewer telephone lines than numbers. In other words if you have 100 employees but they do not all need phone access at the same time you may get say 20 phone lines but 100 DIDs. Everyone has their own number but in reality there are only a handful of physical lines to the Telephony provider. The PBX takes care of the mapping.

This all holds true in VoIP too. All providers provide DIDs since this is needed to map calls from the traditional Public Switched Telephone Network (PSTN) to their VoIP networks. The DIDs are assigned to a gateway in the VoIP network which routes calls from the PSTN to the correct VoIP user. The reverse is also true so that the PSTN user receiving a call from a VoIP user sees the DID number from the VoIP user in their caller id display.

Hope this helps.
Andy