To Rent or Buy the IP PBX? Maybe it’s Both…. Building a VoIP Solution That Enables Both

Topics 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?

Corporate PBX Broadband SOHO 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

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: –Session routing –Network security –Call admission control –Signaling interoperability –Service quality

ESC Session Controller Architecture SIP Softswitch Network Enterprise Peering PSTN Broadband H.323 Network Carrier Peering Broadband NAT Traversal PSTN Orig/Term ESC Softswitch CSC ESC ASP

Core SC vs. Edge SC Core Session Controller (CSC) –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? SIP Ingress Leg H.323 Ingress Leg Call Bridge (IWF) SIP Egress Leg H.323 Egress Leg Routing and CAC Logic INVITE ARQ, LRQ, Q.931 INVITE, REGISTER ARQ, LRQ, Q.931 FCP Dynamic Media Routing Fabric NAT/PAT Static H.323 SIP Unauthorized Media Authorized Media Media Databases

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 HQ PBX VoIP Enabled Router Public Network (PSTN) ISP Data VPN H.323 CSC Unified Messaging System IP Telephone IP PBX Desktop Client IP Telephone IP PBX Desktop Client ITSP H.323 SIP H.323 IP Telephone IP PBX Desktop Client ASP SIP H.323 ESC Hosted PBX SOHO International Sites Domestic Sites Campus PBX ESC Local & LD Untrusted Trusted

Let Service Providers Simplify the Problem CSC TDM Carrier Backbone ESC TDM Termination SS7 SS7 Legacy PBX IP PBX Hosted PBX ESC performs local CAC, signaling adaptation (e.g. H.323/SIP), NAT and Media Firewalling CSCserves as a route engine between IP platforms and service based CAC PBX Tieline Media GW 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