Transcript EI-4 - TMCnet

To Rent or Buy the IP PBX?
Maybe it’s Both….
Building a VoIP Solution That
Enables Both
Topics
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To Rent or Buy the IP PBX?
Barriers to Both
Session Controllers
Enterprise Applications
Carrier Services
To Rent or Buy?
• Both improve user experience, reduce OPEX and offer
similar features
• IP Centrex farms hassles of ownership to service providers
and also has a better disaster/survivability story
• IP PBXs can be used with a range of service providers and
can migrated to gradually.
• Hedge your bets – use IP Centrex to provide services to
SOHO while you IP enable existing PBXs or deploy IP PBX
in larger offices.
Barriers to Both
• Using VoIP interconnects creates some challenges -- TDM
is an implicit firewall and normalizes VoIP traffic.
• Security
– How do calls traverse existing firewalls and NATs?
• Interoperability
– How do calls go off-net?
– How can other SIP applications be leveraged?
– What are the pain points?
VoIP Security
• Firewall implementations are a barrier to real-time services
– Security policies prevent promiscuous and ad hoc connectivity
– Lack protocol awareness for H.323 and SIP
• IP PBX
– Firewall traversal needed to reach the corporate PBX
• IP Centrex
– Multiple NAT traversals required to reach SOHO users
– Firewall traversal needed to reach corporate users
Broadband
Corporate PBX
SOHO
VoIP Incompatibilities
• Applications are SIP based while network infrastructure
and IP PBXs continue to be H.323 dominated
– 90% of VoIP Networks are H.323; 90% of VoIP Apps are SIP
– Prevents enterprises from leveraging SIP apps from carriers.
• Standards are subject to interpretation
– Problem areas: message formats, message order, timing
• Other problem areas arise because of endpoint limitations
– Codec mismatch
– Mismatch of DTMF transport methods
– T.38 fax
Doing Both
• Session Controllers enable carriers and the enterprise to
control, route and manage VOIP traffic in a secure and
seamless manner
• Needed for IP Centrex since IP is the delivery mechanism
– Overcome security issues to reach end-user
– Simplify off-net connectivity to PSTN gateways
• Provides greater ROI for IP PBX deployments since IP can
be used to connect with the user and the network.
– Convert trunks to VoIP by replacing TDM gateways and reduce
access charges by converging voice and data.
What is a Session Controller?
• AKA Border Controller or Session Border Controller
• New breed of networking technology that provides layer 5
routing and control to manage real-time traffic flows in IP
networks
• Technology addresses issues of:
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Session routing
Network security
Call admission control
Signaling interoperability
Service quality
Session Controller Architecture
SIP Softswitch
Network
ASP
CSC
ESC
ESC
PSTN
Softswitch
PSTN
Orig/Term
ESC
ESC
H.323 Network
Broadband
Enterprise
Peering
Broadband
NAT Traversal
Carrier
Peering
Core SC vs. Edge SC
• Core Session Controller (CSC)
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Signaling only platform deployed in the network core
Programmable route engine
Centralized CDR collection
Call Admission Control on a network basis
• Edge Session Controller (ESC)
– Edge Session Controller deployed at the network edge to
manage interconnects (both media and signaling)
– NAT and Media Routing for network security
– Signaling Interoperability and interworking (abstraction layer)
– Call Admission Control on a local basis
– Media processing for specialized applications such as
transcoding
How Does a Session Controller
Work?
INVITE
Call Bridge (IWF)
SIP Ingress Leg
SIP Egress Leg
ARQ, LRQ, Q.931
H.323 Ingress Leg
H.323 Egress Leg
Databases
Routing and CAC Logic
ARQ, LRQ, Q.931
Static
H.323
INVITE, REGISTER
Media Routing Fabric
NAT/PAT FCP
SIP
Unauthorized Media
Authorized Media
Media
Dynamic
Signaling
• Complex because VoIP technologies are
incompatible
– H.323-SIP, H.323-H.323, SIP-SIP, etc.
• Abstracts signaling from routing providing any-to-any
calls
• Multi-service: Video and Voice
Media Routing
• Selective – media flow may be off-net or between
trusted endpoints
• NAT/PAT of media and signaling enables topology
hiding
• Dynamic “pinholes” for media prevents unauthorized
access
• NAT traversal provided for subscribers using
broadband network access
Media Processing
• Media translation applications:
– Normalize media codecs
– DTMF processing
• Selective use limits the number of DSPs needed and
optimizes platform costs
Enterprise VoIP Applications
Untrusted
Trusted
Public Network
(PSTN)
Unified Messaging
System
HQ
IP Telephone
Local & LD
CSC
H.323
IP PBX
SIP
H.323
Desktop
Client
ITSP
ESC
ASP
Campus PBX
SOHO
Hosted
PBX
H.323
SIP
Data VPN
H.323
ESC
SIP
PBX
ESC
VoIP Enabled
Router
Domestic
Sites
ISP
IP PBX
IP Telephone
Desktop
Client
International
Sites
IP PBX
IP Telephone
Desktop
Client
Let Service Providers Simplify the
Problem
Hosted PBX
Media GW
SS7
SS7
CSCserves as
a route engine
between IP
platforms and
service based CAC
CSC
TDM Termination
PBX
Tieline
IP PBX
TDM
Legacy
PBX
Carrier
Backbone
ESC
ESC performs local CAC,
signaling adaptation
(e.g. H.323/SIP), NAT and Media
Firewalling
PBX Tieline
Carrier Services
• Offering managed PBX services
• Hosted PBX or IP Centrex
• Bundle those services with long distance and other valued
added services like teleconferencing
• Early providers: Level3, Masergy, GoBeam
• Trials: SBC, Verizon
Enabling Enterprise VoIP
• Session controllers enables the enterprise to hedge their
bets on IP Centrex and the IP PBX
• Session controllers simplify VoIP deployment by
overcoming issues of VoIP security and incompatibility
• Session controller position the enterprise for the future by
providing a foundation for other real-time IP application
Dan Dearing
Vice President of Marketing
[email protected]