Course11:Advanced - Book on Faxserver

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Book about innovaphone Faxserver Application and FAX-Interface.



The innovaphone Faxserver Application enables to extend the PBX functionality with an E-Mail to Fax Gateway.

Following components are engaged in the process of sending or receiving a fax message:
  • Faxserver Application based on the innovaphone Linux Application Platform
    • SMTP Server
    • WebDAV Server
  • Gateway object in the PBX
  • FAX-interface based on the innovaphone Gateway or IPVA
screenshot.png Faxserver Overview

The Faxserver Application monitors via SOAP the Fax Gateway object for incoming calls trying to deliver a fax or starts a call from the Gateway object for outgoing fax messages.

The FAX-interface, registered at the Gateway object, terminates VoIP calls (RTP/T.38 streams) and converts the payload to a TIFF-file. The TIFF-files are stored on the WebDAV server, located at the same Linux Application Platform as the Faxserver instance.

The Faxserver Application daemon running on the Linux Application Platform converts the TIFF-files to PDF-files and sends them via a SMTP server to the appropriate E-Mail address. The E-Mail address is determined by the User object, which extension was appended to the number of the Fax Gateway object. For outgoing faxes, the Faxserver Application daemon converts the E-Mails and attached documents, received by the SMTP-Server, to TIFF-files and places them on the WebDAV server.

Following animation shows step-by-step how an outgoing fax message is processed by the Faxserver Application:

screenshot.png Sending Fax

An incoming fax message is handled similarly.


System Requirements

To run the Faxserver Application an instance of an innovaphone Application Platform running on a VMWare host or an innovaphone gateway with Linux support is required.

Incoming and Outgoing Fax Calls

To terminate calls to other fax-capable endpoints, an innovaphone gateway or IPVA instance with a FAX-interface is required.

The FAX-interface supports T.38 protocol and "soft-fax" or Audio Fax (FAX via G.711). The option Audio FAX support for FAX-Interface is only available on gateways of IPx10 and IPxx10 series (as well as IP1060) with V11 and newer firmware. Please notice, that for every Fax call via G.711 two DSP channels are required. This means no IPVA can be used for G.711 fax. Audio FAX is only required when sending through a SIP Trunk (when sending through an ISDN or POTS interface, the innovaphone gateway implementing the interface will do T.38).

The number of concurrent Fax calls is limited by the gateway device with FAX-Interface, according the following table:

Device Type
Number of FAX-Channels
100 on VM with512 MB RAM

Incoming and Outgoing Fax Documents

In order to send or receive E-Mails with Fax attachments, an email server with SMTP protocol and authentication support is required (e.g. Microsoft Exchange Server with SMTP Send Connector).

The SMTP authentication is required for incoming emails with documents, that are queued for sending via fax.


For each PBX user a Fax PBX license is required and must be activated on the User object.

Mapping of fax numbers to E-Mail addresses

You may wonder, how the Faxserver Application knows which fax number extension is assigned to the E-Mail address of a PBX user.

In a V10 PBX every User object has a place to store an E-Mail address. You can configure multiple E-Mail addresses at the user object. The first E-Mail address is composed automatically by the PBX, by appending the domain name(i.e. System Name) after the users name. For example, if the System Name of the PBX is and the Name of the User object is john, the resulting E-Mail address of this user will be

screenshot.png composed email address

In order to compose the E-Mail address from the users Name and System Name, the check mark at the Users object must be activated.


Before starting to configure the Faxserver, collect the following information:

  • which Domain name should be used as destination E-Mail address when a user sends a fax?
  • which IP address should be assigned to the Faxserver?
  • which extension number in the PBX will have the Faxserver?
  • which credentials must be used for the SOAP connection at the PBX?

After the requiered information is gathered refer the wiki article fish-help.png Step-by-step Faxserver installation to install and configure the Faxserver Application.


First, try to call the extension number of the Fax Gateway, followed by a Fax enabled User extension, from an external phone - you should hear the typical fax tone.

If not, check the PBX and the Gateway:

  • is the FAX-interface registered on the Gateway object?
  • is a SOAP session of the Faxserver active at the PBX?
  • check the fish-help.png HTTP client settings on the Gateway with the FAX-interface - it should have credentials configured to be able to access the WebDAV server

Next, try to send an E-Mail to an external number followed by the Fax domain (e.g. 012345@fax.domain). A call should be started shortly.

In case that a call to a fax device is established but no fax pages are delivered, check the T.38 setting on the interfaces.

To see what happened with your test fax messages, check the screenshot.png Diagnostics page of the Faxserver Application. There you can see a list of your calls and their state.

Following errors could appear in the list:

Using a Printer Driver to send a Facsimile

As outgoing fax documents can be sent as PDF file to the fax server, you can use just any PDF printer driver with email support to send a fax from arbitrary applications. See fish-help.png Printer driver solution for innovaphone faxserver for an example.
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