Case Study for Large Scale Centralized SIP Trunk ...d2zmdbbm9feqrf.cloudfront.net/2011/las/pdf/BRKUCC-2931.pdfCase Study for Large Scale Centralized SIP Trunk Implementation BRKUCC-2931

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Case Study for Large Scale

Centralized SIP Trunk

Implementation

BRKUCC-2931

Jason Holt

July 19, 2011


Please silence your cell phones

Feel free to step out as needed

This is a non smoking venue

Remember to fill out your Evaluations

Visit the World of Solutions

Questions?

Housekeeping Issues


Understand this Centralized SIP architecture over MPLS

Learn about an alternative Dial Plan solution (pros and cons)

Show design challenges for a centralized architecture

Identify possible issues of Centralized SIP Trunk

Share design ideas and lessons learned

Session Objectives


Case study for a specific architecture and financial customer requirements

Design and lessons learned can be applied to Enterprise environment

It is not about SBC boxes or SIP Service Provider architecture

Design was done in Nov/Dec 2008

Pilot started in Jan 2009 (CUCM 6.x)

CUCM 7.x and 8.x have additional features and options for SIP

Showing a simplified version of the design (several months in 2 hours)

Scope and Context


Customer Requirements

Design Challenges

Dial Plan Design

Call Routing Design

Implementation Issues

Agenda


Customer Requirements


Centralized call control captures an additional 4-8% TCO savings

Cuts administrative overhead by centralizing management and minimizing resources required to update/change services

SIP Trunking provides additional TCO savings of up to 12-26%

• Lowers costs by reducing the number of PSTN circuits

• Reduce administration & maintenance costs of supporting multi-vendor PBXs

• More flexibility & less complexity when provisioning for traffic patterns

Lower Total Cost of Ownership

Comparison of Monthly Voice Connectivity Operating Costs Per Seat (TDM versus SIP)

Cost Category TDM With SIP Trunking

DID $4-6 $5-8

Channel Cost PRI $27-37$3-6.8 (assumes a 5x to 8x reduction in channels

based on concurrent call density)

MPLS data service Not applicable $1.4-2.8 (assumes each branch has 10 to 20 users)

SIP Equipment Not applicable $1-2.1

Total Cost $31-43 $10.4-19.7


Customer Requirements for This Case Study

• 2700 Sites

• 50,000 IP Phones

• UCM 6.1(2) (8.5 Today)

• Unity 5.0 (CUC 8.0 Today)

• CER 2.0(3) (8.0 Today)

• Green Field (Keep existent DID)

• All sites are remote over MPLS

• Hub site for signaling only

• Redundant Applications on two

datacenters (CUCM, CUC, SBC,GK)

• Clustering over the WAN

• US only sites on several states

• PSTN Access over MPLS WAN

• Plan for Future Contact Center

• Centralized SIP trunk (MPLS)

• 10 digit dialing for US PSTN calls

• No local calls

• No local TDM PSTN access

• G.729 for PSTN and inter site

• No Centralized MTP


GK

MPLS

PSTNWest

SBC

East

Cluster 1

A

SBC

Cluster 1

SBC

Datacenter E

GKCluster 2Cluster 2

ASBC

Traditional Topology

Flow Through

or

Media Anchored


PSTN

GK

MPLS

SBC

SBC

West East

SBCSBC

GK

PSTN

Geographical Redundancy

West Datacenter East Datacenter

Fiber

North

Fiber

South

Cluster 2

A

PUB

SUB

MoH

TFT

P

Cluster 1

A

PUB

SUB

MoH

TFT

P

CoW C2

SUBMoH

TFT

P

CoW C1

SUBMoH

TFT

P

MPLS Topology (Requirement)

PSTN


PSTN

GK

MPLS

SBC

SBC

West East

CoW C1

CoW C2

Cluster C1

A

Cluster C2

A

SBCSBC

GK

PSTN

Total of Seven

Clusters

MPLS Topology (Not on the Scope)

PSTN


C1-SUB2-W C1-SUB2-E

C1-SUB3-W C1-SUB3-E

C1-SUB4-W C1-SUB4-E

C1-TFTP-W

C1-SUB1-W C1-SUB1-E

C1-TFTP-E

C1-PUB-W

CUC1-E

CUC2-E

CER1-ECER1-W

CUCM C1

CUCM C1

Unity C1CER C1 CER C1

CUC1-W

Unity C1

DR

Standby

SFTP-ESFTP-W

West Datacenter East Datacenter

GK-W GK-E

SBC

SBC

South

Fiber

North

Fiber

Clusteringover the

WAN

Clustering over the WAN


PSTNPSTN

GK

MPLS

SBC

SBC

West East

SBCSBC

GK

X

MTP

PSTN

RT

P

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Voice Path Requirement (RTP)

Flow Around

or

Media Release


PSTNPSTN

GK

MPLS

SBC

SBC

Datacenter W

SBCSBC

Datacenter E

GK

PSTN

West East

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Signaling Path


Deployment Scenarios

Centralized Deployment Model

Central SIP trunk (Centralized Signaling and Media)

Distributed Deployment Model

SIP trunks per location (Direct Signaling and Media)

MPLS Deployment Model

Centralized signaling, Direct media

Hybrid Deployment Model

Centralized, distributed, PSTN


Design Challenges


Centralized SIP Trunk Design Challenges

DTMF

SRST

Non Ported DIDs

Central Site Device Pool

MoH

FAX


MoH



PSTNPSTN

GK

MPLS

SBC

SBC

West EastDatacenter W

SBCSBC

Datacenter E

GK

PSTN

Hold

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A MoHMoH

MoH

Max Hop (TTL) = 1

Multicast Addr: 239.1.1.1

RTP Port: 16348

Multicast Addr: 239.1.1.1

RTP Port: 16348

X

MoH with Local PSTN Access


PSTNPSTN

GK

MPLS

SBC

SBC


SBCSBC

Datacenter E

GK

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A MoHMoH

RT

P -

Mo

H

Flood Network with

Multicast MoH

Traffic from All Sites

Multicast Between

Customer and

Service Provider

One Single

PSTN Trunk

X

MoH for Centralized SIP Trunk (Distributed)


IP

PSTN

MoH for Centralized SIP Trunk (Unicast)

GK

MPLS

SBC

SBC


SBCSBC

Datacenter E

GK

PSTN

Hold

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A MoHMoH



Central Site Device Pool

MoH Centralized MoH Limited to 50


MPLS

PSTN

Cluster C1

A

Unity

GW

Site A

PSTN

HQ

MoH

Device Pool and Region (CODEC)

HQ Device Pool

GW-HQ or SIP trunk, Unity VM, IP phones, MoH server

G.711/G722 internally, G.729 with other regions

Site A Device Pool

GW-Site-A, IP phones



MPLSCluster C1

A MoH

Site A

DC

Unity

Cluster 2

A

XX DC Device Pool

Unity VM, IP phones, MoH server, SIP trunk

G.711/G722 internally, G.729with other regions


PSTNI P

PSTN


MPLSCluster C1

A MoH

Site A

DC

Unity

Cluster 2

A DC Device Pool

DC IP phones only

G.711/G.722 internally, G.729 with other regions

Multiple Device Pools

Unity, SIP trunks, ICT trunks, MoH server

G.729 only

Site A Device Pool

GW-Site-A, IP phones



PSTNI P

PSTN



Non Ported DIDs

Central Site Device PoolMultiple Device Pools for Devices on Datacenters



SIP trunk provider will not own the DID for some sites

Incoming calls require a local TDM trunk with local carrier

Outbound calls (local, 911 and TFN) cannot be routed via SIP trunk

Consequence

Customer still wants to send outbound calls via SIP trunks

Requirement

Depending on the region, some DID cannot be ported to the SIP Trunk

CLEC does not have an agreement in place to port numbers away with the current ILEC or CLEC providing the service

Restriction

DID Not Ported to the SIP Trunk


IP PSTN

GK

MPLS

SBC

SBC

West East

SBCSBC

GK

Outbound SignalingOutbound Signaling Inbound Signaling

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Call Flow (DID Ported)


IP PSTN

GK

MPLS

SBC

SBC

West East

SBCSBC

GK

TDM

RTP

Inbound Signaling

PSTN

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Call Flow Inbound (To DID Not Ported)


IP PSTN

GK

MPLS

SBC

SBC

West East

SBCSBC

GK

Outbound Signaling

X

LD Trunk (Outbound)

• LD• International

PSTNPSTN

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Call Flow Outbound (From DID Not Ported)


IP PSTN

GK

MPLS

SBC

SBC

West East

SBCSBC

GK

TDM

RTP

• Local Calls• 911 • TFN

Outbound Signaling

PSTN

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Call Flow Outbound (From DID Not Ported)



Requires a Different Call Flow and Different Call Routing

FAX

Non Ported DIDs




Back in 2008/09 the carrier had no support for FAX over SIP trunk

Customer has centralized FAX solution but it is not widely available

Issue

On small sites (about 2000) main FAX is directly connected to POTS line

Additional fax machines in small sites use FXO/FXS on local GW

FXO and FXS used for fax are not controlled by CUCM

Requirements

Support for FAX


MPLS

IP

PSTN

Cluster C1

A MoH

Site A

DC

Unity

Cluster 2

A

N x FXO

(or) PRIPSTN

FAX

Fax Call Flow (FXO/PRI)


FAX over SIP

Centralized fax server with G.711 to SIP trunk

Need dedicated SIP trunks for Fax DID forcing G.711

Distributed fax with G.711 between SIP trunk and remote sites

Need to reserve BW for Fax (CAC + QoS)

Fax can run over the same SIP trunk as voice

Need to detect fax tone and change codec with re-invite

Non centralized FAX still needs BW reservation for G.711

Centralized/Distributed T.38 Fax

Looking for SIP carrier support and working case



SRST

Not Supported on SIP Trunk;

Handled by Site GW


FAX

Non Ported DIDs




MPLS Cluster C1

A MoH

Site A

DC

Unity

Cluster 2

A

N x FXOPSTN

FAXSRST

911 Call Back

Main Number

FXO Port

911 Only

Call Flow on SRST (Small Site)

IP

PSTN


Call Flow on SRST (Medium/Large Site)

MPLS Cluster C1

A MoH

Site A

DC

Unity

Cluster 2

A

N x PRIPSTN

FAXSRST

Inbound

Main Number

911

Local/LD

Intl/TFN

IP

PSTN



DTMF

Limited Access via FXO (Small)

PRI for Medium/Large SiteSRST


Handled by Site GW


FAX

Non Ported DIDs




DTMF over SIP Trunk

H.323 SCCP

RFC2833XIP PSTN

Cluster 1

A

SBCSBC

SIP

SIP SCCP

RFC2833

IP PSTN

Cluster 1

A

SBCSBC

SIP

MTPX

Check Phone Models

Check

Phone Firmware

CUCM Only Accepts

RFC2833 If There Is

a SIP Call Leg

It Was Originally

Designed with H.323



SIP Trunk and Check IP PhoneDTMF

Limited Access via FXO (Small)

PRI for Medium/Large SiteSRST


Handled by Site GW


FAX

Non Ported DIDs




Dial Plan Design


Design Requirements

• 2700 sites

• 50,000 IP phones

• Centralized SIP trunk (MPLS)

• No local TDM

• No 7 digit local dialing

• No 11 digit LD dialing

• 10 digit dialing for PSTN calls

• Same site extension dialing (4 digits)

• Local PSTN access for 911 on SRST only

• Avoid numbers overlap that causes IDT

• Reserve a internal DN range for CC agents

• Alternative for 911 misdialing issues

• Keep existent DID


• 10 Digit DN, PSTN Like

• 9 as access code for

PSTN calls

DN Cannot

Start with 9

• 8 + 10 digit DN

User Doesn’t Know If

Number Is on PSTN

or Another Branch

User Doesn’t Know

If Remote Branch

Has Been Migrated• 9 + 10 digit DN

• 9 as access code for

PSTN calls

• 4 Digits for same site

dialing (last 4 of DN)

4-Digit Extension

Cannot Start with 9

• Same site can use:

* + last 4 digits of DN

User Will

Always Dial 9

• Can use 0 for operator

• Can use leading 1 for

internal/service numbers

Dial Plan Design


Dial Plan Restriction

10-digits dialing for local and long distance calls

Eleven digit and seven digit dialing will not be accepted

All IP Phones will have a 10 digit directory number (DID)

Users will dial 10-digits for IP phones on any cluster

Internal calls to any site will be routed directly via WAN

Same site calls will use an access code plus 4 digit extension

Reserve a range of non-DID DN for future CC agents

Design Two Dial Plans and Present Pros/Cons

Customer Request


Option 1 (DN=10 digit) Access Code 9 and *

First Digit User Dial Description Type

0 0 Operator TP

1 100XXXXXXX CTI Ports/RP… DN/RP

1 1[1-3]XXX Call Park DN

1 14XXXXX Contact Center Extensions DN

9 9.911 Emergency RP (UP)

9 911 Emergency RP (UP)

9 9.[2-9]XXXXXXXXX LD and DN RP/TP

9 9.011! / 9.011!# International RP

# #XXXXXXXXXX Forward VM DN

* *XXXX Site Extension TP

2-8 Not Used Free

Dial Plan Option 1 (Access Code)


Dial Plan 1 (Access Code)

Two Types of Access Code:

• “9” for PSTN calls and Internal DN on other sites/cluster

• “*” for same site extension dialing

Limitations:

• Corporate directory: Use must edit to dial

• Dial back (missed call and received calls): Use must edit to dial

• Discard 9 before routing internal 10-Digit DN: Requires a TP

• System cannot distinguish between PSTN and DN

• Existent 911 misdialing issues

• Cannot use “*” for analog phones or International (+)


Dial Plan Option 2 (PSTN Flat)

Option 2 (DN=10 Digit) PSTN Flat

First Digit User Dial Description Type

0 00 Operator TP

0 011! / 011!# International RP

1 100XXXXXXX CTI Ports/Unity Ports/RP… DN/RP

1 1[1-3]XXX Call Park DN

1 14XXXXX Contact Center Extensions DN

9 911 Emergency RP (UP)

# #XXXXXXXXXX Forward VM DN

* *XXXX Site Extension TP

[2-9] [2-9]XXXXXXXXXX LD and DN DN/TP


Dial Plan 2 (PSTN Flat)

User Dialing:

• Plain 10 digit for PSTN calls and Internal DN on other site/cluster

• “*” for same site extension dialing

Limitations:

• System cannot distinguish between PSTN and DN

• Cannot use “*” for analog phones or International (+)

• Cannot reserve “0” for Operator

• Different user experience: No Access Code, no Sec Dial Tone


Call Routing Design


Intercluster and PSTN Routing

• Regionalize Clusters

• Group sites by State or Region (Area Code)

• Route between clusters by Area code

• Reroute rejected calls from GK or Cluster

• Site DN range segmented (Over 11K RP)

• 11000 prefixes is too much for GK

• Distribute 2700 sites across CUCM clusters

• How to route between clusters?

• Gatekeeper controlled ICT

• All PSTN calls will hit the GK

• Unassigned DN will cause routing loop


PSTN

SBC 2

Cluster C4

A

Cluster C1

A

Cluster C3

A

Cluster C2

A

SBC

SBC

SBC

SBC

Regional Cluster Architecture

Cluster C5

A

SBC 1

GKGK

VA: 276, 434, 540, 571,703, 757, 804

WV: 304

GA: 229, 404, 470, 478, 678,706, 762, 770, 912

AL: 205, 251, 256, 334SC: 803, 843, 864

NC: 252, 336, 704, 828, 910, 919, 980

540-222-5555 919-444-2222

404-555-6666

Less the 200 Patterns

Less the 200 Patterns


GK

MPLS

IP PSTN

SBC

SBC


SBCSBC

Datacenter E

GK

PSTN

Outbound SignalingOutbound Signaling Inbound Signaling

CoW C2

CoW C1

Cluster C2

A

Cluster C1

A

Call Routing


CSS-SITE-X-LD(Device)

Site Specific

PT-Site-X

Non DID DN *222X

Call Park 11XX

Operator

TP 00 => 10 Digit DN

Site Extension

TP *SSXX => 10 Digit DN

CER

RL-ENTIPCCE (Reserved)

RP 14XXXXX

Block

RP [2-8]11

RP [79]00XXXXXXX

RP 976XXXXXXX

RP [2-9]XX976XXXX

TP RP 911

PT-Global

RG

SBC

2

SBC

EAST

SBC

WEST

PSTN SBC

EAST

PSTN SBC

WEST

PT-Internal

All Cluster DN

DID [2-9]XX-XXX-XXXX

Non DID 100-XXX-XXXX

UCCE 14XXXXX

Unassigned DN

TP [2-9]SS-SSS-SSXX

=> 100999????

Unity Call Handler

IP Phones

Route Points

RL-GK RG-GK1

Cluster C4

Cluster C5

Cluster C6

Cluster C7GK-West

GK-East

Cluster C3

Cluster C2

PT-LD

RP [2-9]XX-XXX-XXXX

Cluster Area Codes

RP AAA-XXX-XXXX

International

RP 011! / RP 011!#

TFN: RP 8FF-XXXXXXX

RL

SBC

Outbound Call


919-555-4444

Site Specific


PT-Internal

All Cluster DN



UCCE 14XXXXX

Unassigned DN

TP 919-555-44XX

=> 1009991000

Unity Call Handler

PT-Site-X

Non DID DN *222X

Call Park 11XX

Operator


Site Extension

TP *44XX => 91955544XX

PT-LD

RP [2-9]XX-XXX-XXXX

Cluster Area Codes

RP 919-XXX-XXXX

International

RP 011! / RP 011!#

IPCCE (Reserved)

RP 14XXXXX

Block

RP [2-8]11

RP [79]00XXXXXXX

RP 976XXXXXXX

RP [2-9]XX976XXXX

TP RP 911 CER

RL-GK

RL-ENT

RG-GK

RG

SBC

1

2

RL

SBC

PT-Global

SBC

EAST

SBC

WEST

PSTN SBC

EAST

PSTN SBC

WEST

IP Phones

Route Points

Cluster C4

Cluster C5

Cluster C6

Cluster C7GK-West

GK-East

Cluster C3

Cluster C2

TFN: RP 8FF-XXXXXXX

919-555-4444

408-555-4444

919-777-6666

Outbound Call (Example Same Cluster)


919-555-4444

Site Specific


PT-Internal

All Cluster DN



UCCE 14XXXXX

Unassigned DN

TP 919-555-44XX

=> 1009991000

Unity Call Handler

PT-Site-X

Non DID DN *222X

Call Park 11XX

Operator


Site Extension

TP *44XX => 91955544XX

PT-LD

RP [2-9]XX-XXX-XXXX

Cluster Area Codes

RP 919-XXX-XXXX

International

RP 011! / RP 011!#

IPCCE (Reserved)

RP 14XXXXX

Block

RP [2-8]11

RP [79]00XXXXXXX

RP 976XXXXXXX

RP [2-9]XX976XXXX

TP RP 911 CER

RL-GK

RL-ENT

RG-GK

RG

SBC

1

2

RL

SBC

PT-Global

SBC

EAST

SBC

WEST

PSTN SBC

EAST

PSTN SBC

WEST

IP Phones

Route Points

Cluster C4

Cluster C5

Cluster C6

Cluster C7GK-West

GK-East

Cluster C3

Cluster C2

TFN: RP 8FF-XXXXXXX

408-555-6666

408-555-6666

408-777-8888

Outbound Call (Example Different Cluster)


Site Specific


PT-Internal

All Cluster DN



UCCE 14XXXXX

Unassigned DN

TP [2-9]SS-SSS-SSXX

=> 100999????

Unity Call Handler

PT-Site-X

Non DID DN *222X

Call Park 11XX

Operator


Site Extension

TP *SSXX => 10 Digit DN

PT-LD

RP [2-9]XX-XXX-XXXX

Cluster Area Codes

RP AAA-XXX-XXXX

International

RP 011! / RP 011!#

IPCCE (Reserved)

RP 14XXXXX

Block

RP [2-8]11

RP [79]00XXXXXXX

RP 976XXXXXXX

RP [2-9]XX976XXXX

TP RP 911 CER

RL-GK

RL-ENT

RG-GK

RG

SBC

1

2

RL

SBC

PT-Global

SBC

EAST

SBC

WEST

PSTN SBC

EAST

PSTN SBC

WEST

IP Phones

Route Points

CSS-SITE-X-ENT(Device)

PT-ENT RP [2-9]XX-XXX-XXXX

Cluster C4

Cluster C5

Cluster C6

Cluster C7GK-West

GK-East

Cluster C3

Cluster C2

TFN: RP 8FF-XXXXXXX

Outbound Call (Additional Requirements)


Cluster C4

Cluster C5

Cluster C6

Cluster C7

GK-West

GK-East

Cluster C3

Cluster C2

PT-Internal

CSS-INCOMING

PT-911-CallBack

All Cluster DN



UCCE 14XXXXX

Unassigned DN

TP [2-9]SS-SSS-SSXX

=> 100999????

TP <ELIN>

913XXXXXXXXXX

(One TP per Site)

SBC

SBC

IP PSTN

PSTNGW

Incoming Calls (Cluster)


Implementation Issues


SIP Trunk Issues During Pilot

Voice Quality on Outbound Call Leg

Voice Quality of Recorded VM Messages/Greetings

Outbound Calls Rejected

No Outbound Calls to SBC

Incoming Calls from SBC Stopped Working


No Outbound Calls to SBC



Outbound Calls Rejected

No Outbound Calls to SBC Check If SBC Uses TCP or UDP


PSTN

SBC

Cluster 2

A

Cluster 1

A

SBC

SBC SBC

Incoming Call to Area Code 408

Incoming Call to Area Code 919

West East

NPA 408

NPA 408 NPA 919

NPA 919

No Geographical Redundancy for Incoming Calls

SIP Trunks on CUCM (Inbound)


PSTN

SBC

Cluster 2

A

Cluster 1

A

SBC

SBC SBC

Outbound Call fromArea Code 408

West East

NPA 408

NPA 408 NPA 919

NPA 919

Where Should SBC Send

Outbound Calls?

No Geographical Redundancy for Outbound Calls

SIP Trunks on CUCM (Outbound)


PSTN

SBC

West

Cluster 2

A

Cluster 1

A

East

SBC

SBC SBC

NPA 408

NPA 408 NPA 919

NPA 919Outbound Call fromArea Code 408

Outbound Call from Area Code 919

SIP Trunks on CUCM (Solution)


PSTN

SBC

West

Cluster 2

A

Cluster 1

A

East

SBC

SBC SBC

NPA 408

NPA 408 NPA 919

NPA 919

Outbound Call fromArea Code 408

HMR (Header Manipulation Rule) to Prefix a FQDN

Geographical Redundancy for Outbound Calls


PSTN

SBC 2 SBC 3

Cluster C1

A

SBC

SBCSB

C

SBC

Additional Geographical Redundancy

Cluster C2

A

Added Two More SIP POP on Carrier

Network

SBC 1 SBC 4

Use SIP Option to Check Availability

and Move to Secondary SBC



Outbound calls RejectedDID Assignment on Redundant

SBC or SIP Providers




Multiple SIP trunks between CUCM and SBC

Which SIP trunk will receive the incoming call?

SIP Trunk for Incoming PSTN Calls

CUCM 8.5

Error Message When Configuring Second SIP Trunk with the

Same SIP Sec Profile:

Unmapped Exception the Destination Address "20.126.7.12" Conflicts

with the Destination Address in "TR-EAST-SBC03-EO2". Both Have

the Same Incoming Port "5060" Specified in their SIP Trunk Security

Profiles. Update so that the Destination Addresses and Incoming Ports

Are Unique.


SIP Trunk for Incoming PSTN Calls



Outbound Calls RejectedDID Assignment on Redundant




Which SIP Trunk Handles

Incoming Calls? Check CSS



MPLS

IP PSTN

Cluster 1

A

Site A

DC

Unity

Cluster 2

A

SBC

SBC

PSTN

User Incoming audio to IP Phone is fine but PSTN user receives bad audio

Problem is intermittent

Inbound and Outbound calls

Can happen to any cluster

Issue

Outbound RTP not always correctly marked

Switch configured to mark all RTP packets based on RTP port number (range 16384K to 32768K)

Troubleshooting

Phone sends RTP on non standard port range as requested by far end (SBC)

SBC configured to use port range 10,000 to 40,000

Cause

SBC Chooses Listening RTP Port

IP Phone Sends Audio to SBC Selected

RTP Port

Packets Marked as BE May Be

Dropped

RTP May Be Remarked as

BE




Voice Quality on Outbound Call Leg QoS => Check UDP Port Range

Outbound calls RejectedDID Assignment on Redundant








MPLS

IP PSTN

Cluster 1

A MoH

Site A

DC

Unity

Cluster 2

A

Message or Greeting recorded had lower quality.

Issue

PSTN calls and IP phone calls are G.729.

CUC configured to record messages with G.729

Incoming G.729 audio on Unity had good quality.

Outbound G.729 audio had low quality.

Troubleshooting

CUC converts all audio to PCM before recording on selected format.

Changing CUC to record greetings and messages with G.711 fixed the problem.

Cause

Quality of Voice Mail Messages





QoS => Check UDP Port Range

Record Messages with G.711

Outbound Calls RejectedDID Assignment on Redundant







No DTMF on PSTN Cross Cluster Calls (RFC2833)

No Ring Back on Blind Transfer

Other SIP Trunk Customer on Same Provider May (VoIP) Require G.711

Reroute on Reject Broken

Media Cut Through Delay

No Ring Back on Outbound Calls

SIP Trunk Issues During Pilot (Part 2)

“Very Early Media”


SCCP

Cross Cluster DTMF

SC

CP

X

X

SIP

RFC2833H.323/SCCP

SIP

RFC2833

IP PSTN

Cluster 1

A

SBCSBC

SIP

Unity 2

H.323

Cluster 2

A

Unity 1

SIP

RFC2833

Cluster 1

AUnity

H.323

Cluster 2

A

SC

CP

SCCP


Cross Cluster DTMF (Solution)

RFC2833RFC2833

SIP Unity Pilot

SIP SCCP

RFC2833

IP PSTN

Cluster 1

A

SBCSBC

SIP

Unity 2

H.323

Cluster 2

A

Unity 1

SC

CP


Cross Cluster DTMF (Similar Scenarios)

• Turrets connected via TDM to one cluster but providing devices for sites on other clusters. PSTN incoming SIP Calls re-routed via H.323 ICT.

• Same situation for TDM PBX with DID ranges belonging to multiple clusters.

• Cross Cluster transfer or forwarding of CC calls. Incoming

• Use dedicated SIP Trunks between clusters. Not Scalable.

• Route PSTN calls directly from SBC with more specific

routing. What about internal calls?

• Convert ICT to SIP and use SME to centralize call routing

Alternate Solutions


PSTN

SBC 2

Cluster C4

A

Cluster C1

A

Cluster C3

A

Cluster C2

A

SBC

SBC

SBC

SBC

Cross Cluster DTMF (Similar Scenarios)

Cluster C5

A

SBC 1

GKGK

Turrets

MGCPSIP

H.323

PBX

Contact

Center

H.323

SCCP

IVR



Dedicated SIP ICT Trunk to rRoute Unity RP Across Clusters





SP

VoIP

Delayed Offer to Early Offer Interworking

INVITE (Offer SDP)INVITE

180/200 (Answer SDP)180/200 (Offer SDP)

ACK (Answer SDP)

SBC

SBC

Session Established Session Established

Requires Media Flow Through

(Media Anchored)

SBC Sends Its Own IP Address and RTP

Port on SDP


SP

VoIP

Delayed Offer to Early Offer (Flow Around)


180 (Sess. Progress SDP)180 (Offer SDP)

ACK (Answer SDP)

SBC

SBC

SBC Sends Its Own IP Address and RTP

Port on SDP

Session Established

SBC Sends SDP with IP

Address/Port of IP Phone

200 OK

200 OK

Re-INVITE (New SDP)

RTP (Early Media)


Flow Around(Media Release)

IVR

CUCM Send ACK with SDP


SP

VoIP

Delayed Offer to Early Offer (PRACK)


180 (Sess. Progress SDP)183 (Offer SDP, 100rel)

PRACK (SDP)

SBC

SBC

Session Established

200 OK

200 OK

Re-INVITE (New SDP)

RTP (Early Media)

IP Phone Opens Send and

Receive Channel

IVR



Dedicated SIP ICT Trunk to Route Unity RP Across Clusters



Configure UCM to Use PRAC

(SIP Rel1XX Enabled)



Fast Answer


SP

VoIP

Delayed Offer to Early Offer(Very Early Media)


180 (Sess. Progress SDP)183 (Offer SDP, 100rel)

PRACK (SDP)

SBC

SBC

Session Established

200 OK

200 OK

Re-INVITE (New SDP)

IVR

RTP (Very Early Media)


SP

VoIP

CUCM 8.5 Early Offer

INVITE (Offer SDP)

180 (Sess. Progress SDP)183 (Offer SDP, 100rel) SBC

SBC

Session Established

200 OK200 OK

IVR

RTP (Very Early Media)



No Ring Back on Blind Transfer

Dedicated SIP ICT Trunk to Route Unity RP Across Clusters

Annunciator

Reroute on Reject Broken Caused by Annunciator

Need Dedicated MRGL Group



Configure UCM to Use PRAC

(SIP Rel1XX Enabled)


Flow Through

Media Anchored


Fast Answer


New Developments


PSTN

SBC 2

Cluster C4

A

Cluster C1

A

Cluster C3

A

Cluster C2

A

SBC

SBC

SBC

SBC

Contact Center SBC Separation

Cluster C5

A

SBC 1

SBC

SBC

Contact

Center


PSTN

SBC 2 SBC 3

Cluster C4

A

Cluster C1

A

Cluster C3

A

Cluster C2

A

SBC

SBCSB

C

SBC

New Clusters

Cluster C5

A

SBC 1 SBC 4

Added Two More Clusters (C6/C7) for

Expected Growth and Scalability

Cluster C6

A

Cluster C7

A

Cluster C8

A

Added Cluster C8 (Innovation Cluster)New and Advanced

Solutions in Production


• Centralized Dial Plan

• Can use SIP Trunks between cluster

• Multiprotocol

• Move 3rd party systems out of cluster

o Fax

o Turrets

o Contact Center

o PBX

• Better dial plan management and interface then GK/SME

• Reduced number of SIP trunks on cluster

Benefits of SME Architecture


PSTN

SBC

SBC

Cluster C5

A

Cluster C4

A

PBX

Turrets

Contact

Center

H.323

Cluster C3

A

Cluster C2

A

SME

A

MGCP

SIP

SIP

SIP SIP

SIP

SIP

SIP

SBC

SBCSB

C

SBC

SIP SIP

SME Architecture

PBXH.323

Cluster C6

A

SBC

SBC

IVR

SBC

SBC

Cluster C7

A

Cluster C1

A

Cluster C8

A

FAX

SIP

SIP

SIP

SIP

SIP

Covered on BRKUCC2450SME Design


Deployment model: SIP over MPLS

Design challenges

Flat dial plan without access code for PSTN

Possible issues and workarounds

Test on lab and pilot until you break something

Define a very comprehensive pilot

Summary


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Case Study for Large Scale Centralized SIP Trunk ...d2zmdbbm9feqrf.cloudfront.net/2011/las/pdf/BRKUCC-2931.pdfCase Study for Large Scale Centralized SIP Trunk Implementation BRKUCC-2931

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