Course12:Advanced - 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 (cf. fish-help.png Gateway/Interfaces/Physical) for the FAX-Interface is only available on newer gateways with built-in DSPs. You will see a "n channels for the innovaphone faxserver using T.38 or via G.711" remark in the respective data sheet (e.g. in fish-help.png IP3011 Features EN).

Please note that for every Fax call via G.711 two DSP channels are used on the gateway the FAX-Interface runs on. This means no IPVA can be used for G.711 fax. Audio FAX is only required to send fax 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. To find out which number of Fax channels are supported by a particular device type please refer to the fish-help.png Technical Data Pages (aka. product data sheets) on the innovaphone Wiki.

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.

How e-Mail communication works

The innovaphone Faxserver acts as Server for “Mail to Fax” and “Fax to Mail”. Therefore it must be able to send and receive e-Mails to and from the customers’ Mail-Client.

This Chapter describes how it works.

Declaration of the Faxserver Mail-Domain

The first and very important step is to choose a Mail-Domain for the Faxserver. It’s not necessary that this is an official Mail-Domain, but it must never be an existing domain!

Mostly it’s a very good choice to use your existing domain (where you are the owner) and declare a subdomain, i.e. “” if your company is the owner of “”.

Fax to Mail Setup

With Fax to Mail, the Faxserver sends an incoming Fax to the Mailserver of the Customer. A direct Mailclient connection to the Faxserver does not work for receiving eMails from the Faxserver!

The customers Mailserver must accept SMTP eMails from the Faxserver. Therefore you need mostly a valid user account for the Mailserver.

How it Works:

1. The Faxserver on the innovaphone Linux AP receives an incoming Fax and creates the sender address (From) and the recipients address (To). With this information he is sending an e-Mail via SMTP.

a) For the sender address the Faxserver is adding his Domain Part to the Calling Number (i.e.
b) The recipients address the Faxserver gets from the PBX Users Object(i.e.

2. The Relay-Server on the innovaphone Linux AP forwards this Mail to the Customers Mailserver

a) The DNS Name or IP-Address of the customers Mailserver has to be declared

b) The Sender Domain (Faxserver Mail Domain) is used for identification

c) Credentials to login to the Mailserver can be declared (Mostly any valid user account)

3. The Mailserver receives the Mail via the Relay-Server

4. The Mail-Client receives the Mail from the Mailserver

Fax to Mail

Mail to Fax via Mailserver Setup

With Mail to Fax via Mailserver, an administrational access to the Customers Mailserver is needed. The configuration depends on the kind of Mailserver has to be done by the Mailserver Administrator.

Example for Exchange:

How it Works:

1. The Mail-Client sends a Mail to “phonenumber@faxdomain”

a) His sender address (From) must be the same like in the PBX for this User (i.e.

b) The recipients (To) address must be “phone number” @ “Fax Domain” (i.e.

2. The Mailserver of the customer forwards the Mail to the Faxserver.

a) The Fax Domain (i.e. must be forwarded to the Faxservers’ IP-Address

b) Credentials to login to the Faxserver must be declared. If this is not possible, this step can be skipped

3. The Faxserver receives the Mail and creates the Fax

a) The recipients address must have the correct domain Part

b) The sender address is checked against the PBX

c) The credentials must be valid or the IP-Address of the Mailserver must be added to the authorized Hosts
Mail to Fax via Mailserver

Mail to Fax directly from Mail-Client

With Mail to Fax directly from the Mail-Client, no Mailserver configuration needed. The configuration is made locally on each client and depends on the kind of Mail-Client.

This works only for sending Mails to the Faxserver and does not work for receiving Mails from the Faxserver!


How it Works:

1. In the Mail-Client, a new Mail-Account for the Faxserver has to be created.

a) The Mail address must be the same like in the PBX for this User (i.e.

b) The Faxservers IP must be used for Inbound and Outbound Servers

c) Credentials to login to the Faxserver must be declared

2. The Mail-Client sends a Mail to “phonenumber@faxdomain”

a) His sender address (From) must be the new Mail-Account

b) The recipients (To) address must be “phone number” @ “Fax Domain” (i.e.

3. The Faxserver receives the Mail and creates the Fax

a) The recipients address must have the correct domain Part

b) The sender address is checked against the PBX

c) The credentials must be valid

Mail to Fax directly from Mail-Client


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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