What is Calling Number Display (Caller ID)?
Support for routing incoming faxes using Calling Number Display (commonly called Caller ID in the USA) has been added. New rules will make this possible from within the Inbound Rules Editor. CND support within RelayFax requires the CND
service provided by your telephone company (usually at an extra monthly
charge). Also, the fax modem must have support for detecting and
preserving CND data so that RelayFax can acquire it. Note that most of the cheaper modems on the market today do not have CND
capability and those modems that do, typically will not have that
support enabled by default. Consult your modem manual for the proper
INIT string command, which enables CND support. You
will likely need to add this command to the INIT string from within
RelayFax (see the manual on how to edit your modem's INIT string).
CND
information is transmitted from the phone company to your fax modem in a
packet of information located between the first and second Rings.
Therefore, you must configure your modem to allow at least two Rings
before answering the call. You can configure this using a new setting
within the Modem Properties dialog.
CND data
can be transmitted in a variety of formats. It can be sent as a raw byte
stream, in single-message format, or multi-message format. To make full
use of RelayFax's CND routing capabilities you must configure your modem to provide CND
data in multi-message format. Consult your modem manual for the proper
INIT string settings required to achieve this (for example +VCID=1). In
multi-message format most modems append 'labels' to the raw CND
data elements in order to make it easier to read. However, there are no
uniform standards governing what these labels should be. This results
in different modems using different labels for each piece of CND information. For example, one modem might label the CND
number as 'NUMB=' while another would use 'CALLER NUMBER:'. You will be
able to read the labels your modem uses by watching an incoming call
being processed by RelayFax. RelayFax needs to know what these labels
are so it can parse the number and name elements from the CND
data. Once you determine the labels your modem uses you can enter this
into new controls found within the Modem Properties dialog. Technically,
RelayFax should be able to acquire the CND data in raw
format, which doesn't require any labels however experimentation has
discovered that some modems modify, even the raw data before passing it
to RelayFax! This makes parsing problems at the application level
inevitable.
All Inbound Rule actions are eligible for use with CND routing. In addition, one special action is available for use exclusively with CND routing. Since CND detection takes place prior to answering the call you can use the 'Do no answer incoming call' action with CND
based rules. When an incoming call is ignored as a result of such a
rule the call is not answered and will ring until the remote side gives
up. While the phone is ringing you may see one or more error messages
such as 'unspecified modem error' or 'timeout during fax send/recv'.
These error messages are of no real concern. As of the time of this
writing these messages have not yet been suppressed even though no
actual error is taking place. The presence of these error messages does
not affect the performance of the software in any way (except taking up
space in the log file needlessly).
A few new CND related macros are available for DAT file use. $CNDDATA$ returns all of the CND information provided to RelayFax by your fax modem. The '|' char is used in place of line breaks. $CNDNAME$ returns only the CND name element. Finally, $CNDNUMBER$ returns only the CND number element. The $CNDNAME$ and $CNDNUMBER$ macros only work properly when the CND name and number labels are properly configured within the Modem Properties dialog.