# FAX Over IP Support - Description

## Description

This feature supports real-time, Group 3 facsimile (FAX) communication over IP networks using FAX Relay (T.38 standard protocol). FAX Relay (T.38) allows you to transmit and receive facsimile over IP trunks between FAX machines on MiVoice Business (3300 ICP Release 9.0 or later) systems.

## Supported Configurations

You can configure the MiVoice Business network to allow facsimile to be sent over the

- PSTN using analog signalling

- IP network using G.711 pass-through, or

- IP network using FAX Relay (T.38)

The following illustrations show simple examples of these configurations. It is possible to configure network configurations that are much more complicated than the configurations detailed below.

## FAX Over PSTN

In this configuration, FAX data is sent using analog signalling. The system connects to the PSTN via LS, PRI, or T1 trunks. With this method, it is more expensive to send faxes long distances over the PSTN than it is to send them over the IP network.

## FAX Over IP Network Using G.711 Pass-Through

This method uses T.30 protocol with G.711 pass-through to send FAX over IP trunks using the LAN and WAN. The MiVoice Business systems in the network must be running 3300 ICP Release 7.0 or later.

- Note: A VEC module is required to support FAX over an IP network using G.711 pass-through.

This method has the following advantages:

- allows you to send faxes between MiVoice Business systems over the IP network

- reduces the cost of sending long-distance faxes because the data is sent over the IP network and not the PSTN

However, this method has the following disadvantages:

- LAN and WAN must be engineered to meet the LAN quality guidelines specified in the MiVoice Business Engineering Guidelines.

- Voice packets carrying fax on the network cannot be compressed.

- Quality and performance of fax transmission using G.711 pass through is inferior to the quality and performance provided by FAX Relay (T.38) protocol, especially over WAN links because the likelihood of network issues is higher.

## FAX Over IP Using FAX Relay (T.38)

FAX Relay (T.38) is the preferred method because the

- quality and performance of FAX transmission is superior to that of the G.711 pass though method, especially over WAN links

- LAN and WAN does not have to be engineered specifically to support this method of FAX transmission.

The following diagram illustrates four different ways that FAX Relay (T.38) can be employed to support fax transmission:

1. FAX machine connected to a T.38 protocol enabled MiVoice Business system.

2. FAX call transferred by MiVoice Business to a T.38 protocol enabled gateway.

3. FAX machine connected directly to a T.38 protocol enabled gateway.

4. Internet Aware FAX (IAF) machine with built in T.38 gateway functionality

Related Topics

- FAX Over IP Support - Conditions

- Configure FAX Over IP Support