Hardware requirements
Zetafax supports most active ISDN controller cards supporting CAPI (with fax support). The following sections give details of other possible hardware configurations.
BRI fax boards and Active ISDN Controllers
The most common way of installing DID is to use a basic rate ISDN (BRI) Brooktrout intelligent fax board. These boards connect directly to a BRI line and interpret the DDI or MSN information. In some countries, BRI is often called ISDN-2 as it is supplied with two channels (or telephone lines).
PRI fax boards
For companies who want to implement DID on a larger scale, it is possible to install a higher density fax board capable of supporting many more fax lines by using a Primary rate interface (PRI) fax board. PRI is an ISDN service which supports up to 30 channels and which supports DDI routing. In addition, both PRI and BRI can provide features not available over traditional analog telephone lines such as 'advice of charge'.
DID fax board
In North America and some other countries DID information can be delivered by the phone company over a special DID analogue telephone line used for incoming calls only. There are models of Brooktrout and Gammafax intelligent fax boards for connecting directly to DID lines to interpret the DID information.
PBX with DDI/DID
If your phone system (PBX) already supports Direct Dialing Inwards (DDI or DID), you can add DDI/DID routing for fax very simply. The PBX needs to be configured so that calls to any of the fax DDI/DID numbers you allocate are routed to the phone extensions used by the Zetafax Server.
Note: The number of DDI/DID fax numbers is independent of the number of fax modems and lines in use. On Zetafax Servers using more than one fax modem the extensions would need to be configured so that if one was engaged the PBX moved on to the next (sometimes called divert on busy or hunt groups ).
When Zetafax answers the call the PBX also must be configured to identify the extension (DDI/DID) number being dialed, by sending a series of DTMF tones. This is the method used for connecting to voicemail systems, and is supported by most PBXs which support DDI/DID.
Call Equisys or your local supplier if you want specific advice about the configuration required.
Fax modem
The fax modems or intelligent fax boards used for DID routing, using either of the two options above, must support DTMF tone recognition in fax mode. All Brooktrout and Gammafax intelligent fax boards do support DTMF tone recognition. Check with Equisys for a full list of supported modems with this feature.
ISDN router
ISDN (Integrated Services Digital Network) comes to the rescue of people who do not have a PBX which handles direct dialing, or who want to keep fax separate. By installing an ISDN line with a fax router box, you can allocate a series of DDI numbers without using the PBX.
The fax router box sits between the ISDN line and the fax modem or fax board. When an incoming call is answered, it identifies the DDI number dialed by sending DTMF tones before connecting the call.
Many telephone companies offer an alternative to DDI on ISDN lines called Multiple Subscriber Numbering (MSN). It is suitable where only ten or fewer separate numbers are required. Fax routers can usually handle both MSN and DDI.