Sub-address routing
Sub-address routing is the most direct of the automatic routing methods available, allowing the sender to specify the intended recipient directly. There are four different methods of doing this.
DID routing
Many companies already have a phone system (PBX) where each extension can be dialed directly from outside the company, rather than having to go via the switchboard. The technology behind this is called Direct Dialing Inwards (DDI) or Direct Inward Dialing (DID), and is as applicable to fax as it is to voice calls.
This is the most direct of the inward routing methods. Each user is given their own fax number - not a separate fax line, just their own number. Faxes sent to that number are routed directly to the user.
The number of fax numbers allocated is independent of the number of fax lines on your Zetafax system - all you do is define a table of fax numbers, giving the Zetafax user account corresponding to each one.
If your phone system supports DDI/DID for telephone calls already, it can probably be configured simply to allow DDI/DID for fax. If you do not already have DDI/DID you can install a separate digital telephone line (ISDN) or analogue DID telephone line to support it just for fax. Details of both these methods are given below.
DTMF routing
The method Zetafax uses for DDI/DID routing is to recognize DTMF tones sent to the Zetafax Server just after it answers the call, telling it what number was dialed. These are the musical tones generated by modern phones when the number keys are pressed.
Even without giving each user their own fax number, you can still get the same effect by getting the sender to key in extra digits after Zetafax answers the call. This is normally done by adding them to the fax number, after a few pause characters. Because of the relatively high level of sophistication required this is suitable for expert fax senders only!
Station ID suffix
If you are sending a fax to another Zetafax system, you can specify the recipient's username to cause the fax to be routed directly to that user. This is done by adding the username to the end of the destination fax number, separated by a colon; for example 123 4567:Brian. You can also set up other routing names for use with this mechanism such as extension numbers or descriptive names such as SALES.
The username or parameter is sent to the remote fax system by adding it to the end of the station identifier , or CSID . This is the identifier programmed into all fax machines and printed on the top line of faxes they send, and is usually set to the sender's fax number. Sometimes called colon routing, this routing method is also supported for faxes sent to and from other PC fax systems.
T.30 sub-addressing
The ITU Group 3 fax T.30 specification has been extended to allow for sub-addressing in addition to the basic fax number. At first only fax software will support this, but in the future expect to see fax machines with an extra button or two. It works in the same way as Sender ID extension routing.
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