MVA Jump Start

Module6

PSTN Integration

Module Overview

• Connecting to the PSTN

• Connecting to the existing PBX

• M:N Interworking Routing

• Call Routing Reliability

Lesson 1: Connecting to the PSTN

• Background Definitions

• UCOIP

• Typical Legacy Enterprise PBX

• Decision 1: Legacy PBX integration

• Decision 2: POTS/TDM or SIP Trunking

• Direct connect via a Gateway

• Direct Connect via SIP Trunking

Background Definitions

• Public switched telephone network (PSTN)

• Private Branch eXchange (PBX)

• Voice over Internet Protocol (VoIP)

• Session Initiation Protocol (SIP)

• Internet Telephony Service Provider (ITSP)

UCOIP

• Unified Communications Open Interoperability Program

Qualified

Gateway

Qualified

PBX

Supported

PBX

http://technet.microsoft.com/ucoip

Typical Legacy Enterprise PBX

PSTN

Dialing Habits

4 digit internal extensions

9 for an outside line

3 digits + extension for other locations

Class of Service

Inbound/Outbound

Local, National

Class of Service

Outbound only

Local, National,

and International

Numbering Plan

31-20-500 1000 to

+31-20-500 1999

Decision 1: Legacy PBX integration

PSTNPSTN

Connect Lync to the Legacy PBX

Connect Lyncdirectly to the PSTN

Decision 2: POTS/TDM or SIP Trunking

Connect via SIP Trunk

Connect via Gateway

PSTN

PSTN

SIP TDM

Direct connect via a Gateway

• A gateway is a physical device that connects two incompatible

networks

• The gateway translates signaling and media between Lync (SIP) and

the PSTN

• Use supported gateways (UCOIP)

PSTN

SIP TDM

Lync Pool

Lync

Mediation

Server

Qualified

PSTN

Gateway

Direct Connect via SIP Trunking

• IP connection that establishes a SIP communications link between

your organization and an Internet telephony service provider (ITSP)

beyond your firewall

• Use supported SIP Trunking Provider (UCOIP)

PSTN

SIP TDM

Lync Pool

Lync

Mediation

Server

Qualified

IP-PSTN

Gateway

Session

Border

Controller

(SBC)

VPNEnterprise Network ITSP Network

Lesson 2: Connecting to the existing PBX

• Connecting through PBX via SIP

• Connecting through PBX via Gateway

• PSTN Sizing

• Inter-Trunk Routing

• Routing of IP-PBX Calls to PSTN via Lync

• Routing of IP-PBX Calls to another IP-PBX via Lync

• Configuring Inter-Trunk Routing

• Mediation Server

• Media Bypass

Connect through PBX via SIP

PSTN

Lync Pool

Qualified or

supported

IP-PBX

Lync

Mediation

Server

SIP TDM

Connect through PBX via Gateway

PSTN

Lync Pool

TDM or

unsupported

PBX

Lync

Mediation

Server

SIP TDM

Qualified

IP-PSTN

Gateway

PSTN Sizing

1. In replacement scenarios, existing call volume is known

2. Account for new behaviors and features:

• Simultaneous ringing

• PSTN conferencing

• Dial-in audio conferencing

• Leverage the Lync Server 2013 Planning Tool

• Use Erlang B calculations when appropriate

Inter-Trunk Routing

Lync Server 2013

Inter-trunk Routing

IP-PBX to IP-PBX

Peer to Peer Routing

without Lync

Routing of IP-PBX Calls to PSTN via Lync

PSTN

Lync Pool

Lync

Mediation

Server

Lync

Mediation

Server

Qualified

PBX

Qualified

PBX or

Gateway

Media

Inbound

Trunk

PSTN

UsageRouting

Outbound

Trunk

Routing of IP-PBX Calls to another IP-PBX via Lync

Lync Pool

Lync

Mediation

Server

Lync

Mediation

Server

Qualified

PBX

Media

Inbound

Trunk

PSTN

UsageRouting

Outbound

Trunk

Qualified

PBX

Configuring InterTrunk Routing

• Use the Lync Management Shell

1. Configure a Voice route

2. Add a PSTN usage to a trunk configuration:

• New -PSTNUsages property has been added to CSTrunkConfiguration

• Use the Lync Control Panel

New-CsVoiceRoute -Identity RedmondRoute -PstnUsages @{add=“Redmond"}

-PstnGatewayList @{add="PstnGateway:redmondgw1.contoso.com"}

Mediation Server

• Collocation vs. standalone– Collocation can offer significant server count reduction

– Standalone may be preferable for network zone placement or workload

isolation

• Media bypass and scalability– Scale based on hardware and transcoding mix

– For planning, don’t count calls with media bypass

• Pool vs. single server– If configuring your Lync pool for DNS load balancing, does your gateway or

SIP trunk support DNS load balancing?

– Is Enterprise Voice resiliency important?

Media Bypass

http://technet.microsoft.com/en-us/library/gg398703.aspx

Lesson 3: M:N Interworking Routing

• Interworking Routing − History

• Trunk and IP-PBX Interworking

• Trunk and IP-PBX Interworking – Real Life

• Configuration Details

• Trunks and Resiliency

• Multiple Sites to the Same Service Provider

• M:N Interworking Routing –Trunk Definition

• Auxiliary Calling Information

Interworking Routing − History

Office Communications Server (OCS) 2007 R2:

One Mediation Server associated with one PSTN gateway, and vice versa (1:1)

Lync Server 2010:

Multiple PSTN gateways can be associated with the same Mediation Server pool (1:N); a

single PSTN gateway is associated with a single Mediation Server pool; a single SIP listening

port on the Mediation Server and on the gateway is used in the association

Lync Server 2013:

Introduces M:N Inter working routing. A particular PSTN gateway can be associated with

multiple Mediation Server pools or the same Mediation Server pool with multiple unique

associations.

Trunk and IP-PBX Interworking

Trunk 1

Trunk 2

Trunk n

Qualified

IP-PBX

Lync

Mediation

Server

Configured Trunk

Trunk and IP-PBX Interworking – Real Life

PBX-10

PBX Extension

PBX Extension

MTP-2

MED-10

Trunk 1MED-10<->PBX-10

PBX-10 port : 5060Signaling IP : PBX-1Media IP : MTP-1

Trunk 2MED-10<->PBX-10

PBX-10 port : 5061Signaling IP : PBX-1Media IP :

Media Bypass

Media Bypass

MTP-1

PSTN GatewayPBX-10

MTP-2

5060

5061

Configuration Details

• Topology Builder:– Define the PSTN Gateway and Trunks

• Define the MTP as the Alternate Media IP-Address

• Use different gateway listening ports for each Trunk

– Publish the topology

• Windows PowerShell:– Identify the Trunk IDs

– Use Windows PowerShell to configure Media IP Addresses for the remaining

trunks

– Verify the Media IP address for the trunks

Trunks and Resiliency

Mediation

Server MS1

Gateway GW1

Mediation

Server MS1

Gateway GW2

Trunk2

Trunk1

Trunk3

Po

rt

AP

ort

C

Po

rt

BP

ort

E

Multiple Sites to the Same Service Provider

Lync Pool

Site 01

Mediation Pool

SBCsbc1.provider.com

Site 02

Mediation Pool

Trunk 1 Trunk 2

PSTN

MPLS

M:N Interworking Routing –Trunk Definition

Trunk consists of the following mapping:

{Gateway FQDN, port} <-> {Mediation Server FQDN, port}

Auxiliary Calling Information

Lync Server 2013

PSTN Phone

+1 (999) 555 2001

Incoming Call to

+1 (989) 555 0200

PSTN Phone

+1 (999) 555 1000

User Bob

+1 (989) 555 0200

Simultaneous Ring:

+1 (999) 555 1000

INVITE sip:+19995551000@192.168.1.41;user=phone SIP/2.0

FROM: sip:+19995552001@contoso.com;user=phone

TO: sip:+19995551000@192.168.1.41;user=phone

HISTORY-INFO:

sip:+19895550200@se01.contoso.local;user=phone

ms-retarget-reason=forwarding,

sip:+19995551000@se01.contoso.local;user=phone

P-ASSERTED-IDENTITY:

<tel:+19995552001>

SIP Header sent to 19995551000

1

2

Lesson 4: Call Routing Reliability

• Fast Failover & Options Polling

• Call-Routing Reliability – Lost connection

• Call-Routing Reliability – Gateway Down

• Call-Routing Reliability & Retries

• Call-Routing Reliability – Next-Hop Proxy

• Voice Routing Coexistence

Fast Failover & Options Polling

• Gateway Log

• Mediation Server Log

1d:0h:12m:15s OPTIONS sip:192.168.1.41 SIP/2.0FROM: <sip:se01.tailspin.local:5068;transport=Tcp;ms-opaque=6b773cd98097b3f8>;epid=BE80B79150;tag=cdee90d70TO: <sip:192.168.1.41>CSEQ: 3 OPTIONSCALL-ID: 598db21985cb4d38a5e89a410987464aMAX-FORWARDS: 70VIA: SIP/2.0/TCP 192.168.1.52:59546;branch=z9hG4bK3b462b11CONTACT: <sip:se01.tailspin.local:5068;transport=Tcp;maddr=192.168.1.52>CONTENT-LENGTH: 0USER-AGENT: RTCC/5.0.0.0 MediationServer

1d:0h:12m:15s SIP/2.0 200 OKVia: SIP/2.0/TCP 192.168.1.52:59546;branch=z9hG4bK3b462b11From: <sip:se01.tailspin.local:5068;transport=Tcp;ms-opaque=6b773cd98097b3f8>;epid=BE80B79150;tag=cdee90d70To: <sip:192.168.1.41>;tag=1c1952373857Call-ID: 598db21985cb4d38a5e89a410987464aCSeq: 3 OPTIONSContact: <sip:192.168.1.41:5060;transport=tcp>Supported: 100relAllow: REGISTER,OPTIONS,INVITE,ACK,CANCEL,BYE,NOTIFY,PRACK,REFER,INFO,SUBSCRIBE,UPDATEServer: Audiocodes-Sip-Gateway-/v.5.80A.053.005

Call-Routing Reliability – Lost connection

Lync Mediation

Server Pool

MS-02

MS-01

Front End Server

Qualified

Gateways

GW-01

GW-02

GW-03

options

options

options

options

Route Policy:

For the example session only

Gateway GW-01 and GW-03

in that order can be used

SIP Configured Trunk

503 response

Control messages

No longer accessible

Call-Routing Reliability – Gateway Down

Lync Mediation

Server Pool

MS-02

MS-01

Front End Server

Qualified

Gateways

GW-01

GW-02

GW-03

Route Policy:

For the example session only

Gateway GW-01 and GW-03

in that order can be usedoptions

options

options

504 response

SIP Configured Trunk Control messages

No longer accessible

Call-Routing Reliability & Retries

Invite

183 responseFailed Connection

10 sec timer: start

Timer: stop

Lync Server 2010(FE) (MS) (GW)

Invite (trunk 1)

183 responseFailed Connection

10 sec timer-1: start

Timer-1: continues

Cancel (trunk 1)

Invite (trunk 2)

183 response

18x response

Invite

18x response

Timer-1: expires

10 sec timer-1: start

Timer-1: continues

Timer-1: Stops

Lync Server 2013(FE) (MS) (GW1) (GW2)

Call-Routing Reliability – Next-Hop Proxy

• The Mediation Server tracks its next-hop proxy and backup next-hop

proxy by sending out periodic options polls: – Backup next-hop proxy is defined by Pool Pairing

• If the primary next-hop proxy is found to be down (failure to answer

to five options polls in a row), new invites from gateways are sent to

the backup next-hop proxy

• Additionally, a 10-second timer is used for incoming calls, so if the

primary next-hop proxy is used for a call and no SIP response is

received within this time, the call is rerouted to the backup next-hop

proxy

Voice Routing Coexistence

Outbound Calls Home Server

Mediation Server

Lync Server 2013 2013 2013 Supported

Lync Server 2013 &

Lync Server 2010

2013 2010 Supported

2010 2013 Supported

Lync Server 2013 &

OCS 2007 R2

2013 2007 R2 Supported

2007 R2 2013 Not Supported

Inbound Calls Mediation Server

Next-hop Server

Home Server

Lync Server 2013 2013 2013 2013 Supported

Lync Server 2013 &

Lync Server 2010

2013 2013 2010 Supported

2010 2010 2013 Supported

Lync Server 2013 &

OCS 2007 R2

2013 2013 2007 R2 Supported

2007 R2 2007 R2 2013 Supported

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