Equisys technical notes

Technical guidance, explanations and fixes for our products

FIX: Inward routing fails with ZYXEL 2834I ISDN modem if configured to use Class 1



ID: ZTN1038

This Zetafax technical note applies to:

  • Zetafax 5.5 and later


When a ZyXEL 2834I ISDN modem is used for receiving faxes the DID (number dialled) information is not passed to Zetafax, so automatic inward routing does not work.

This is confirmed by checking the [ROUTING] section of the control file for the received fax (zfax\USERS\username\Z‑ IN\~RECDxxx.CTL), which shows that although the fax number of the remote fax may be present, the "DTMF" field giving the dialled number is empty.

Configuring the modem to use Class 2 (using the "edit modem" dialog in the Zetafax Configuration program) causes the dialled number to be passed correctly.


Modems have two different modes of operation for responding to commands from the computer - "long replies" and "short replies".

Earlier versions of the Zetafax Class 1 driver always selected "short reply" mode, while the Class 2 driver used "long reply" mode for the ZyXEL modem.  However, the ZyXEL modem only passes DID information when in "long reply" mode.


The behaviour of the Class 1 driver has been changed with release 6.00e to use "long reply" mode if the modem is configured as a ZyXEL.

To resolve this issue, update the FCLASS device controller module (DEVFC.EXE) to version 6.00e or later. 


This has been corrected in Zetafax version 6.00e of the Class 1 driver.

Last updated: 12 January 2000 (GC/GW)

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