[February 22, 2007] VOIP SBC-Session Border Controllers - SC-Session Controllers – Get VoIP Certified Now Tweet VOIP SBC-Session Border Controllers - SC-Session Controllers – Get VoIP Certified Now By Thomas B. Cross – TECHtionary.com This information was developed for a lesson in the BCR onsite course and the NACSE online course called Channel Provider & Partner Strategies for VoIP course written by the course instructor Thomas B. Cross. The purpose of this lesson is to give specific guidance to planners of VoIP systems regarding session controllers and international standards for VoIP. According to one enduser, "The primary function of the SBC-Session Border Controller is to serve, basically, as a SIP aware NATing Firewall." SC-Session Controllers or SBC-Session Border Controllers are access devices that operate at Layer 5 Session Layer, whereas routers operate at Layer 3 Network. Some of the key functions are: - Dialect Conversion - SIP-to-H.323 and other translation. - Protocol conversion - inband DTMF to out-of-band - dialed number translations. That is, the SC integrated proxy server forwards the SIP invite to the H.323 gateway. - CODEC conversion - COmpression-DECcompression of analog voice packets to various types of ITU standard digital voice compression standards such as G.711 (64 KBPS PCM-Pulse Code Modulation), G.723 (5.3 and 6.3 KBPS), G.726 (16, 24, 32 and 40 KBPS ADPCM-ADaptive PCM), G.728 (16 KBPS CELP-Code Excited Linear Prediction), G.729/a (8 KBPS ADCPM) and others. - Firewall - upon completion of call setup signaling, two-way RTP-Real Time Protocol voice messages are sent and controlled via the SC based on administrative security policies. Some of the other SBC/SC functions are: - Secure network peering - private and public to enhance performance - Topology hiding - using various types of inter-AS-Autonomous System features as well as separating media (voice) and hide signaling (IP addresses) data streams (traffic) - Border call routing - routing at AS level rather than with interior routing protocols - Interoperability - access/restrict to reduce voice spam - QoS & Call Admission Control - load/jitter correction - Billing systems interoperability - reduce billing errors - NAT-Network Address Translation - routing for maximum performance - CALEA-Communications Assistance for Law Enforcement Act - Compatibility with billing - Dialect conversion - Protocol conversion - Codec conversion - Firewall restrictions Various types of stateful (interconnect different networks such as H.323, MGCP-Media Gateway Control Protocol and SIP-Session Initiation Protocol (News - Alert)) and stateless (same networks) Session Controllers exist depending on the VoIP Network features required. For additional information and animated explanation of the concepts presented in this article, please go to http://www.techtionary.com For more information on the online course, click here: http://www.techtionary.com/nacse/nacse-nvbe.htm For the onsite course, click here: http://www.techtionary.com/taa/bcr.htm Session Initiation Protocol (SIP) X SIP is the real-time communication protocol for VoIP. SIP is a signaling protocol for Internet conferencing, telephony, presence, events notification (emergency calling) and instant messaging. SIP...more Internet Protocol (IP) X IP stands for Internet Protocol, a data-networking protocol developed throughout the 1980s. It is the established standard protocol for transmitting and receiving data in packets over the Internet. I...more Voice over IP (VoIP) X A real-time communications system that converts voice into digital packets containing media and signaling data that travel over networks using Internet Protocol....more H.323 (H.323) X This is an introduction to H.323 which is an International Telecommunications Union standard - www.itu.org. Since H.323 represents many different protocols such as voice, control, video, whiteboardi...more Quality of Service (QoS) X This is an introduction to the planning for QoS and Service Level Agreements. Simply, your performance is QoS and the guarantee is the SLA. That is, if you are not receiving the desired QoS from your ...more [ Back To TMCnet.com's Homepage ]