Gateways are devices that convert media streams from one set of communications standards to another and include media gateways, call agents, signaling gateways, translators, and mixers.
- When a host sends media from one point to another, media passes through networks that will have different encoding, signaling, and bandwidth requirements. As media travels through networks, gateways are devices that adjust to the different network signaling requirements and convert media streams from one set of communication standards to another. Gateways include media gateways, call agents, or media gateway controller or softswitch, signaling gateways, and translators and mixers.
Various protocols are involved as well. Signaling transport, or SIGTRAN, is a telephony protocol that transports SS7 signals through the internet. Media Gateway Control Protocol or Megaco, works with H.323, or SIP. And call control protocols include SIP, H.323, and Skinny. A phone call can travel through various networks that include the public switch telephone network, the internet, and a LAN.
As we look at this complex drawing, let's step through a call. A call might start at the public switch telephone network. It will then have to pass through a switching service point and then go to SS7. That SS7 signal will have to go through a signaling gateway where it becomes Sigtran as it travels across the internet. Once in a local area network, it will hit the call agent, or a media gateway controller.
Signaling then becomes session initiation protocol, or H.323, as it communicates with another call agent or a media gateway controller. Media will have to be transformed as well. As we see the data coming off of the public switch telephone network, it's in the form of time division multiplexing. As it passes through the media gateway, it will then transport it into real time transport protocol.
A complex network will involve gateways and protocols to transport telephony data.
Lisa Bock compares the traditional Public Switched Telephone Network (PSTN) to VoIP, and discusses the framework and components necessary for VoIP to be possible. She reviews codecs, including characteristics such as bitrate and voice quality; protocols for setup, communication control, and data transport; and media gateways, signaling protocols, and intermediary systems such as translators and mixers. Lisa then reviews business integration and the importance of conducting a needs analysis and network assessment prior to implementation. Learn about the many value-added services UC can provide, such as integrating VoIP with email, billing, management software, and other customer management systems. Lisa wraps up with a discussion on how ensuring quality of service (QoS) in a VoIP network minimizes latency and jitter and the importance of VoIP security to prevent malware, impersonation, hijacking, and denial of service attacks.
- History and evolution of PSTN
- UC overview and components
- Gateways, including signaling gateways, translators, and mixers
- Integrating VoIP and UC into your business network