DID fax routing

Direct Inward Dialing (DID) fax routing is a variation on the standard fax routing application.

In this case, the caller is given a DID number to call that is directly mapped to a fax mailbox.  This makes it easier for callers to program their fax machines to auto-dial the recipient and send the fax, since they don't have to dial the main number and navigate the auto attendant.

The catch is that your telephone switch must support Direct Inward Dialing for this to work, and not all switches do.  Specifically, it must be able to translate the DID number to a virtual extension (that is, an extension that exists in software only) that is forwarded to voice mail.  This virtual extension would be paired with a fax mailbox on the voice mail system (VMS).

For example, the Avaya Definity provides exported extensions and the Avaya MAGIX and LEGEND switches provide MFM ports; both are types of virtual extensions.  In the switch programming menus, there are options for creating the given type of virtual extensions and for mapping the DID numbers to them.  When a call arrives on one of these DID numbers, the switch will translate the DID number into the mapped virtual extension and use the translated number when sending the inband codes to the VMS.

Note: Some switches, such as the Avaya PARTNER, do not provide virtual extensions and so cannot support DID fax routing.

The figure below provides an overview of DID fax routing call flow.