Sip trunking slides_-_ot_partner_conference

Fax over IP and SIP
Trunking

© COPYRIGHT 2012 DIALOGIC, INC. ALL RIGHTS RESERVED. | www.dialogic.com

Topics

SIP trunks
Overview of FoIP technology
Factors influencing FoIP success
Considerations before choosing a SIP trunk provider

2 © COPYRIGHT 2012 DIALOGIC, INC. ALL RIGHTS RESERVED. | www.dialogic.com

What is SIP Trunking

Alternative to business PSTN services
Analog FXO trunk replacements
T1/E1 PRI trunk replacements
Generally lower cost as compared to
traditional PSTN services

Leverages broadband data connections
Converged voice and data services
Shared bandwidth
Dynamically allocated


Legacy PBX with TDM (PRI) Trunk

Enterprise

Public
Telephone TDM
Network
Legacy TDM
PBX

OpenText
Fax Servers

Recipient
/ Sender
conventional
fax machine

Application Storage
Servers


Replace PRI on Legacy PBX with SIP Trunk

Enterprise

IP Service Gateway
Provider SIP
TDM

Public
Telephone Legacy TDM
Network PBX

OpenText
Fax Servers

Recipient
/ Sender
conventional
fax machine Application Storage
Servers


FoIP server connected to IP-PBX

Enterprise

IP Service Border Element
Provider SIP

Public
IP-PBX OpenText
Telephone Fax Servers
Network

Recipient
/ Sender Application Storage
conventional Servers
fax machine


SR140 Directly connected to a SIP Trunk

Enterprise

Provider SIP

Public
OpenText
Telephone Fax Servers
Network

Recipient
/ Sender Application Storage
fax machine


Overview of FoIP Technology


FoIP Techniques

G.711 (T.30 Fax Pass-Through)
ITU-T recommendation for Pulse Code Modulation (PCM) of
voice frequencies
Fax treated as a VoIP call; encode the fax audio for IP
transport

T.38 Fax Relay
ITU-T recommendation for real-time fax communication over
IP networks
Encapsulate the T.30 fax using a data communications
method


Fax over IP and G.711 Fax

Digital fax data is converted to PCM audio stream and sent as Real-time
Transport Protocol (RTP) packets

Challenges
Some network impairments, such as packet loss and jitter, can impact fax
much more than voice
Techniques used by VoIP gateways to improve voice quality, such as packet
loss concealment and dynamic jitter buffers, can adversely affect fax


Addressing the Challenges of G.711

Most gateways offer a G.711 Fax Pass-Through mode that can be
enabled (V,152) to improve fax quality/success; this mode:
Disables the voice enhancing techniques on fax calls
Employs a large, static jitter buffer

T.38 was introduced as a ITU-recommended procedure for
transporting fax over IP networks


T.38 Fax

Designed to address FoIP issues, including network impairments
Can tolerate Internet-level packet loss, very high delays, and jitter
Much lower bandwidth requirements than G.711
Optional redundancy mode
Usually implemented and enabled

Challenges
Not all SIP trunk providers offer T.38, but the number is growing
Not all SIP and T.38 implementations are alike; SIP Forum is
working to address this


Factors Influencing FoIP Success


Factors Influencing Success – Impairment Levels

Network conditions based on ITU G.1050 definitions
Single Burst
Network type Network Round Trip Latency*
Packet Loss Packet Loss

40 to 200 ms (regional) Random loss
Well Managed IP Network < 0.05%
180 to 600 ms (intercontinental) only

100 to 200 ms (regional)
Partially Managed IP Network < 2% 40-200 ms
180 to 800 ms (intercontinental)

Unmanaged IP Network 40-10,000
100 to 1000 ms < 20%
(open Internet) ms
*not including transcoding, jitter buffers, or response generation (supports real-time applications with strict constraints)


Factors Influencing Success – Impairment Levels

Network conditions based on ITU G.1050 definitions
Single Burst
Network type Network Round Trip Latency*
Packet Loss Packet Loss

40 to 200 ms (regional) Random loss
Well Managed IP Network < 0.05%
180 to 600 ms (intercontinental) only

100 to 200 ms (regional)
Partially Managed IP Network < 2% 40-200 ms
180 to 800 ms (intercontinental)

Unmanaged IP Network 40-10,000
100 to 1000 ms < 20%
(open Internet) ms
*not including transcoding, jitter buffers, or response generation (supports real-time applications with strict constraints)

Typical SIP Trunk


Sample Dialogic Lab Testing Results
Packet Loss: T.38 vs. G.711 Pass-Through

T.38 completion rates
remained above 90% at 2%
2% packet loss

2%
G.711 Pass-Through
completion rates dropped
drop below at 2% packet
below 60%
40% at 2%
packet lossloss


Sample Dialog Lab Testing Results
Burst Loss: T.38 vs. G.711 Pass-Through

remained above 90% at
25 ms burst packet loss

G.711 Pass-Through
completion rates drop at
25 ms burst packet loss


When to Consider G.711 Pass-Through

When the gateway or SIP trunk does not support T.38
AND, you have a well managed network
Considerations:
Setting jitter buffers to a fixed size that is greater than the
amount of jitter present on the network
Optimizing the network to prioritize fax traffic to prevent
packet loss
Selecting network elements that are fax-aware


FoIP Research White Paper

Considerations for Using
T.38 versus G.711
for Fax over IP

Abstract: This white paper compares
the performance of the two principal
options for implementing fax over an
IP network: Fax-Relay (T.38) and Fax
Pass-Through (G.711)

Available from OpenText


Considerations Before Choosing a SIP Trunk Provider


Replace PRI on legacy PBX with SIP Trunk

Enterprise

IP Service Gateway
Provider SIP
TDM
T
Public D
Telephone Legacy TDM M
Network PBX

Dialogic-
based Fax
Servers
Considerations:
SIP Trunk configured for
T.38 or G.711
Gateway support fax
Recipient
/ Sender
conventional
fax machine Application Storage
Servers


FoIP server connected to IP-PBX

Enterprise

Provider SIP

Public Dialogic-
IP-PBX based Fax
Telephone Servers
Network

Considerations:
T.38 or G.711
IP-PBX support T.38 or
Recipient G.711
/ Sender Is IP-PBX on Interop list Application Storage
fax machine


SR140 Directly connected to a SIP Trunk

Enterprise

Provider SIP

Public Dialogic-
based Fax
Telephone Servers
Network Considerations:
T.38 or G.711
Is registration and/or
authentication required
for SIP trunk
Is it SIP over TCP or UDP
(TCP support available soon)
Recipient Does Border Element
/ Sender support VoIP/SIP? Application Storage
fax machine
Will Border Element pass
T.38 traffic


SIP Trunks: Factors Influencing End-to-End Success

SIP trunk provider
T.38 support
• In the access points and core
• Redundancy
Number and type of call segments
Peering
Endpoints
Gateway/SBC
Fax speed (V.17, V.34)
T.30 interoperability
Fax document specifics: length, image
Network
Geographic range
Managed (access point, enterprise)
Impairment levels (QoS)


SIP Trunks: Factors Influencing End-to-End Success

Careful selection of SIP trunk provider
Specifically offer support for fax, preferably T.38
SLA, access options, and historical data to support QoS
Geographical coverage matches your needs

In most cases, choose T.38
G.711 can be successful with a well managed network

Check the Dialogic website for interoperability testing for
network elements and SIP trunk providers
If provider or device is not on this list, work with Dialogic to discuss the
possibility of arranging a Dialogic Interoperability Test


Interoperability

Dialogic maintains a list of equipment and SIP trunks that have
been successfully tested with Dialogic® Brooktrout® SR140 Fax
Software: http://www.dialogic.com/interoperability/fax.htm


Dialogic, Veraz, Brooktrout among others as well as related logos, are either registered trademarks or trademarks of Dialogic Inc. and all companies controlling, controlled
by, or under common control with Dialogic Inc. (“Dialogic”). The names of actual companies and products mentioned herein are the trademarks of their respective owners.
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