Xerox PHASER 3100MFP User Manual [nl]

Xerox Multifunction Devices

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This document applies
to the Xerox products
indicated in the table
below. For some
products, it is assumed
that your device is
equipped with the
appropriate option to
support this document.

x Phaser 3100MFP

th

, 2009

…for the use

A Guide to Faxing Over IP
Networks – Phaser 3100MFP

Overview

This guide is intended for network administrators, or service providers, with responsibility
for configuring settings within an IP network expected to provide telephony service to a
Xerox fax device.

The Phaser 3100MFP fax feature is capable of standard G3 fax operation (maximum
data rate 14400 bps) or Super G3 fax (maximum data rate
33600 bps). It is designed to connect to analogue telephone
lines that carry audible frequencies (i.e. speech). Fax data is
converted into audible signals for transmission through the
Public switched telephone network using a modem.

What is Voice over IP (VoIP)?

Internet Protocol (IP) networks carry data in a digital packet format. Voice signals must

Analogue

VOICE

Digitizing Codec

Digital

FAX DATA

Analogue Modulation

be encoded into this digital format before being transmitted over IP.
This encoding also compresses the data to reduce the load
(bandwidth) on the network. This function is provided by an access
device that supplies the conversion interface – see Network Setups
(page 4).

What is Fax over VOIP (FoVoIP)?

The fax is connected to the VoIP interface on the network and is treated like a standard
voice call. The analogue fax signals are encoded into a digital
format, just as for a voice call. The voice encoding compression
severely limits the fax speed, and network quality issues that
are acceptable to voice calls usually cause the fax to fail – see
Quality of Service (page 2).

FoVoIP is often called Fax Pass-through.

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Digital

FAX DATA

Analogue Modulation

Digitizing Codec

What is Fax over IP (FoIP)?

In FoIP, the fax data is sent in its raw digital form across the IP network. As with all IP
data, it is divided into a packet structure. Because the fax data is in its raw state it uses
less bandwidth and can employ redundancy (data duplication) or Forward Error
Correction to improve reliability. Sometimes the fax data rate is reduced to further limit
bandwidth usage. It is thus normal that SuperG3 is not supported, and so it should be
disabled on the Phaser 3100MFP to avoid compatibility issues. FoIP is sometimes called
Fax Relay. There are proprietary versions (e.g. Cisco) but the cross-vendor standard
from the International Telecommunications Union is called T.38 (which is supported by
the Sagem Fax ATA 101S).

It is possible to enable the Phaser 3100MFP for FoIP operation using an IP terminal
interface. This interface recognizes the signals from the fax machine and decodes them
back to the raw fax data, in real time. A similar interface may be required at the other end
of the communication. The interface must also convert fax data received from the
network back into analogue signals that the machine will understand. To ensure
successful faxing, it is important that all network elements are configured correctly.

Quality of Service Requirements

What is Quality of Service?

Quality of Service (QoS) is a prioritized or guaranteed level of service for a particular
network user or application (e.g. VoIP or FoIP). QoS places demands on characteristics
such as available bandwidth and the level of network impairments. Network impairments
can sometimes be controlled by Service Level Agreements with private network
providers, but are generally impossible to control over public internet-wide
communications. For this reason, fax communications across the internet are not
recommended. Bandwidth and communications protocols, such as FoIP, can be more
easily managed by the end to end capabilities (and configuration) of the network
interfaces

What Are Network Impairments?

Data in an IP network is divided up into packets. As each packet of data moves through
the network it can be subject to various impairments that can affect some, all, or none of
the packets at any given time. These are:

Packet Loss: This is the most serious impairment and means that the data stream

cannot be fully recombined at the other end. FoVoIP is very sensitive to
this and a small level can often lead to failure. If FoIP is configured with
redundancy, relatively large levels of loss can be accepted.

Packet Delay: Some delay in the packet stream is unavoidable; the level will depend on

the length of the network path and the level of congestion within the
network. Again, FoVoIP is sensitive to this, since the underlying fax
protocol has strict timing requirements. FoIP uses methods to work
around this, avoiding failure of the fax communication.

Packet Jitter: Jitter is a variation of delay between packets. Above a certain level the

affected packet(s) will be considered lost and FoVoIP audio will be
broken, resulting in fax failure. FoIP reliability will be better due to lower
bandwidth demands against the buffer memory available.

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