sip trunking slides_-_ot_partner_conference

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

Fax over IP and SIP Trunking

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

Topics

SIP trunks

Overview of FoIP technology

Factors influencing FoIP success

Considerations before choosing a SIP trunk provider


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

Recipient

/ Sender conventional

fax machine

Public

Telephone

Network TDM

Application

Servers

Storage

OpenText

Fax Servers

Legacy TDM

PBX

Enterprise


Replace PRI on Legacy PBX with SIP Trunk

Recipient


fax machine

SIP

Public

Telephone

Network

Gateway

Application

Servers

Storage

Legacy TDM

PBX

TDM

IP Service

Provider

OpenText

Fax Servers

Enterprise


FoIP server connected to IP-PBX

Recipient


fax machine

SIP

Public

Telephone

Network

Application

Servers

Storage

Border Element IP Service

Provider

OpenText

Fax Servers IP-PBX

Enterprise


SR140 Directly connected to a SIP Trunk

Recipient


fax machine

SIP

Application

Servers

Storage

Public

Telephone

Network


Provider

OpenText

Fax Servers

Enterprise


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

Network type Network Round Trip Latency* Single

Packet Loss Burst

Packet Loss

Well Managed IP Network 40 to 200 ms (regional)

180 to 600 ms (intercontinental) < 0.05%

Random loss only

Partially Managed IP Network 100 to 200 ms (regional)

180 to 800 ms (intercontinental) < 2% 40-200 ms

Unmanaged IP Network

(open Internet) 100 to 1000 ms < 20%

40-10,000 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

Network type Network Round Trip Latency* Single

Packet Loss Burst

Packet Loss

Well Managed IP Network 40 to 200 ms (regional)

180 to 600 ms (intercontinental) < 0.05%

Random loss only

Partially Managed IP Network 100 to 200 ms (regional)

180 to 800 ms (intercontinental) < 2% 40-200 ms

Unmanaged IP Network

(open Internet) 100 to 1000 ms < 20%

40-10,000 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

drop below 40% at 2%

packet loss

G.711 Pass-Through

completion rates dropped

below 60% at 2% packet

loss


remained above 90% at 2%

packet loss 2%

2%


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

G.711 Pass-Through

completion rates drop at

25 ms burst packet loss


remained above 90% 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

Recipient


fax machine

SIP

Public

Telephone

Network

Gateway

Application

Servers

Storage

T

D

M

Dialogic-

based Fax

Servers

Legacy TDM

PBX

TDM

IP Service

Provider

Considerations: SIP Trunk configured for T.38 or G.711

Gateway support fax

Enterprise


FoIP server connected to IP-PBX

Recipient


fax machine

SIP

Public

Telephone

Network

Application

Servers

Storage

Dialogic-

based Fax

Servers

Border Element


IP-PBX support T.38 or G.711

Is IP-PBX on Interop list

IP Service

Provider

IP-PBX

Enterprise


SR140 Directly connected to a SIP Trunk

Recipient


fax machine

SIP

Application

Servers

Storage

Public

Telephone

Network

Dialogic-

based Fax

Servers


Provider


Is registration and/or authentication required for SIP trunk

Is it SIP over TCP or UDP (TCP support available soon)

Does Border Element support VoIP/SIP?

Will Border Element pass T.38 traffic

Enterprise


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

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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