A SIP trunk is a direct connection between organizations and an IP Telephony Service Provider (ITSP). SIP Trunk enables customers to extend VoIP calls to the PSTN beyond firewall without using an on-premise IP-PBX or gateway.

1. Benefits of SIP Trunking for
Office Communications Server

2. Content
• Benefits of SIP Trunking
• Qualified SIP Trunking Service Providers
• More Information
• Appendix
− Technical considerations for SIP Trunking deployment

3. Benefits of SIP Trunking
What is SIP Trunking?
A SIP trunk is a direct connection between organizations and an IP Telephony Service Provider (ITSP).
SIP Trunk enables customers to extend VoIP calls to the PSTN beyond firewall without using an on-
premise IP-PBX or gateway.
SIP Trunking benefits:
• Save money on calling services: SIP Trunk connections for international and long distance
calling can be significantly less than with circuit switched provider.
• Eliminate PSTN gateways: Eliminate gateway management and administration cost and centralize
technology management to bring more flexibility in infrastructure design.
• Eliminate BRI and PRI subscription fees: Replace costly BRIs, PRIs with SIP Trunking. Don’t
need to buy lines in blocks of 24 or 30. Instead, buy the SIP trunk bandwidth you need at better prices
• Eliminate a redundant network: Consolidate telephone and data network into a single, IP based
network reducing cost of redundant OA&M.
• Extend to news services from ITSPs: SIP trunks can also carry other SIP based traffics beyond
voice such as multimedia conferences, user presence information. With a SIP Trunk in place, you can
extend to additional services from service providers such as e911, multi media conferencing, etc.
“Lionbridge, a leading content provider reduced telephony bills by 60 to 80% and
eliminated U.S.$1.4 million of PBX charges a year by using SIP Trunking for Office
Communications Server 2007 R2” Find details here

4. SIP Trunking Providers
X implies general geographic coverage of the region
Qualified Sales Contact Geographic Coverage*
Service NA EMEA Asia LATAM
Provider
Global James.Harney@Globalcrossing.com US Western Singapore
Crossing Europe
Intelepeer SIP@intelepeer.com US
Interoute One Tony.Rogers@interoute.com X
Sprint valerie.webster@sprint.com US
Thinktel sales@thinktel.ca Canada
Verizon US Southeast: Gordon.littley@verizonbusiness.com US Western
US Northeast: frank.a.ciccone@verizonbusiness.com Europe
US Central: ray.herr@verizonbusiness.com
US West: albert.lao@verizonbusiness.com
EMEA:
Michael.van_zetta@verizonbusiness.com
Swisscom In progress to get contact information X
Telenor In progress to get contact information X

5. More Information
• Microsoft UC Open Interoperability Program (UCOIP)
• SIP Trunking whitepaper
• Customer Case studies
“Leading Content Provider Reduces Telephony Connection Charges Up to 80 Percent
with SIP Trunking… click here for more”

7. SIP Trunking Architecture Considerations
• Deployment model dictates End-to-End (E2E) support responsibility
between Microsoft, Service Provider (SP) and Customer
• Upstream IP Telephony Service Providers look like a “Gateway” to on-
premise Mediation Server
• Preferred SIP Trunking deployment model supports SBCs at the SP
core. Deployment option is provided for SP-owned premise-based
gateway scenario.
• Office Communications Server Edge Servers must be used to manage
enterprise network edge access to Office Communicator clients and
Office Communications Server federated networks

8. Option #1: Qualified Service Provider, no Gateway
1. Microsoft supports “Qualified Service Provider Interface” via UC Open Interoperability Program
2. SBC offers access to the Service Provider “core” network
3. Mediation Server and core network SBC interoperate via SIP-TCP/UDP and RTP (G.711)
4. Office Communications Server provides network edge access to Office Communicator
clients and Office Communications Server federated networks
Service Provider & Microsoft Supported Components
DMZ
SBC
Service Provider
Core Network
VPN
TCP/UDP
OCS Network
TCP /
G.711
Service
Provider MPLS
Mediation OCS UC endpoints
Network Server Servers
OCS Edge
Servers
OCS Federated
Network UC endpoints
MICROSOFT CONFIDENTIAL

9. Option #2: Managed Router with E2E Support
1. SBC offers access to the Service Provider “core” network
2. Mediation Server and core network SBC interoperate via SIP-TCP/UDP and RTP (G.711)
3. Office Communications Server provides network edge access to Office Communicator clients and
Office Communications Server federated networks
4. Managed router could transcode G.711 to another codec (G.729?) with tradeoff in bandwidth vs.
scalability
Service Provider & Microsoft Supported Components
DMZ “SP/MSFT
demark point”
SBC “SP Managed
Service Provider
VPN Router” OCS Network
Core Network
TCP/UDP TCP /
G.711
Service
Provider MPLS
Mediation OCS UC endpoints
Network Server Servers
OCS Edge
Servers
Note: It is optional to use the “SP Managed
Router” for Office Communications Edge
OCS Federated Server Connectivity.
Network UC endpoints
MICROSOFT CONFIDENTIAL

10. Option #3: Qualified Gateway, unqualified Service Provider
1. Microsoft supports “qualified gateway interface” via UCOIP
2. “Certified gateway” provides link to Service Provider “core” network
3. Mediation Server and the “certified gateway” interoperate via SIP/TCP and RTP
(G.711)
4. Office Communications Server provides network edge access to Office
Communicator clients and Office Communications Server federated networks
SP/Customer Supported Microsoft Supported
DMZ “SP/MSFT
demark point”
SBC
Qualified
Service Provider
Core Network
Gateway OCS Network
“Any” SP TCP
/G.711
and media
Service
Provider MPLS
Mediation
Mediation OCSOCS UC endpoints
Network Server
Server Servers
Servers
UC endpoints
OCS Edge
Servers
OCS Federated List of prequalified gateways:
Network UC endpoints
MICROSOFT CONFIDENTIAL
http://technet.microsoft.com/ucoip/