Outbound Faxes IP Routing

This section describes how to configure Digital Fax to properly interact with the PBX or voice gateway, in terms of protocols and routing.

VoIP configuration can be controlled through the "IP Routes" Service Parameters setting. From the home page select "Digital Fax" ⇒ "Application Settings" ⇒ "IP Routes".  

WARNING: you have to stop and restart the Digital Fax service from the web interface after any change done in this page.

Limitation: +E.164 numbering doesn't work for outgoing faxes, due to a Microsoft Fax limitation. If a destination fax number is entered in +E.164 format, it is converted by replacing "+" with "00" (for example +44 ⇒ 0044)

Protocol Parameters

In this section you can choose between SIP and H.323, depending on the calling platform or media gateway in use.

The two options related to FoIP negotiation: "Allow G.711 for outgoing faxes" and "Disable T.38 for incoming faxes" can typically be left unchecked for most telephony systems. If you are leveraging a SIP provider which does not support T.38 protocol, please check both options..

Set IP Routes

In this section, you have the possibility to fine tuning the routing of outbound faxes, based on different factors:

Default Route

By default, Digital Fax routes all outgoing faxes to one IP address. This is called the Default Route, and typically this is the IP address of the PBX or Voice Gateway used for PSTN routing.

Multiple routes and Least Cost Routing

Digital Fax T.38 engine can route the outgoing fax calls to many different IP address. Each of these addresses is a physical device which can be a PBX or a Voice Gateway supporting T.38 or G.711 pass-through fax transmission.

Each route might include the first digits of the CALLED number. E.g. you can configure it so that all the outgoing fax calls that have a recipient's telephone number beginning by 06 are routed to a specific gateway.

For each entry, you need to populate the "Prefix" and the "IP" fields, then click "Add".

You can add the same route multiple times associated with different IP addresses, to handle Fallback routes for high availability. Digital Fax will try to route outgoing faxes towards the first destination. If the routing fails, it will try the next one.

If no IP route is matched, then the call is forwarded to the Default Route.

Routing Parameters

In this section, you can add a prefix to outgoing fax numbers (like a "9" to reach PSTN): please select the "Global" PBX routing type, enter the required prefix and press "Save".

Please leave the "Network Routing Type" to "External (off-net) faxes only"

These parameters affect off-net outgoing faxes only, leveraging Print To Fax, Web To Fax and Email To Fax methods.

You can find some alternative configuration samples in this KB article.