Frequently Asked Questions

Does Fax Server Pro support ISDN?

Fax Server Pro supports an ISDN adapter with a T.30-compatible CAPI 2.0 driver. Not every card can be used: Some are only able to fax with a manufacturer-supplied software. You can check if a given card has a T.30-compatible CAPI by downloading the free CapiInfo utility. For fax polling, the B3 protocol "T.30 with Extensions" is required.

  • Cards for one S0/T0 line can typically send and receive on both B channels simultaneously. However, in most cases (like AVM-Fritz) it is not possible to combine two or more passive cards in one PC since their driver does not support this.
  • Multi cards like the Primux-2S0 or -4S0 allow sending and receiving on four resp. eight channels. These adapters are now also available as PCI-E (PCI Express) cards.
  • S2M cards like Primux-1S2M or -2S2M can send and receive on all 30 resp. 60 channels of one resp. two primary-rate lines. They require a PC CPU with 1.5 GHz or faster and at least 512 MB of RAM.
  • ISDN routers like RVS-COM can be used if they implement a LAN CAPI interface with T.30 support, e.g. with a DSP module for decoding fax tones. They are an alternative if internal ISDN cards cannot be used e.g. because the server is running in a virtualized environment.

The following shows you how to configure the AVM ISDN FRITZ USB modem with Fax Server Pro:

  1. Install AVM ISDN CAPI Port Driver

  2. Test the installed modem:
    Open the Windows Device Manager, you will see the AVM ISDN Custom Config Modem installed on your system:


    Right-Click the AVM ISDN Custom Config modem, click Properties menu, in AVM ISDN Custom Config Properties dialog box, select Diagnostics tab, there's a Query Modem button in this tab. If the modem is correctly installed, the list box under the button will display a list of AT commands and the modem's actual response to them when you clicking the Query Modem button.
    You should find the AT+FCLASS=? command with the 0,2 value line in that list box. That means this kind of modem supports Class 2 standard only.
  3. In Fax Server Pro, open the Fax Device Settings window, click Configure Manually button to add the Modem manually:


    Finally, don't forget to set the Fax Class to Class 2. If you not sure what the Init string is, just leave it blank or contact us for help!