On a recent installation we were told there was a DID number when in fact it was a DOD number and the client didn’t know the difference.
DID – Direct Inward Dial (also known as DDI)
DID handsets, attached to an OnPrem or Hosted PBX, have separate phone numbers that can be dialed directly by an external caller.
In this sense, the incoming call is routed by the PBX directly to the handset.
When a call is made from a DID handset the recipient is presented with the main PBX number and not the individual DID number. This scenario is typically useful when the DID number needs to be kept private for all but a few important clients and nuisance calls could be filtered by Reception.
DOD – Direct Outward Dial
DOD handsets have the ability to dial out directly but presents the DOD number to the caller’s recipient. This enables the recipient to call back the DOD number.
DOD is useful in larger organisations where a DOD number can be attached to handsets within separate departments, e.g. each department has a designated number. This is the preferred method for operating a telephone answering service.
DOD is also used if a FAX machine, with a DOD number, is attached to the PBX.
Nuisance calls cannot be filtered because there is no Reception service.
IVR – Interactive Voice Response (including auto-attendant / digital receptionist)
A message is presented to the caller with a scenario like ‘press 1 for sales, 2 for accounts …’ where a response by keypress or voice recognition routes the call to the correct destination.
This is a popular choice where direct external access to handsets is unavailable, possibly because there is only one number available, but can be annoying to the caller when waiting to hear the desired option. Nuisance calls are not filtered by Reception.
(Note: IVR can be more complex that auto-attendant, click here for more information).
As it suggests an incoming call is answered by a person who manually routes the call to the correct destination.
There are differing views on this with respect to the caller experience, but is preferred for filtering unwanted calls. It is also preferred, possibly in conjunction with DID and IVR but not DOD, for operating a service desk where incoming calls have to be manually logged.