VoIP

Choosing a Transport (VOIP)

CSIs are made up of network transports (lines or channels) and the carrier’s equipment used to terminate these lines. Each CSI has multiple carrier transports to offer any customer. A transport is a physical or wireless channel (or aggregate of contiguous channels) that supports the transmission of electrical, optical data, telemetric data, voice, or video […]

CSI: Telephony (VOIP)

All types of networks operate within a much larger structure known in the telecommunications industry as a carrier services infrastructure (CSI). The carrier services infrastructure is an abstract concept for most people. As you begin to discover the various VoIP network types (such as DSL or a T1 line), it’s essential to know about each […]

The Five Golden Rings of CSI (VOIP)

It’s useful to understand from which CSI a network transport service comes. The CSI to which a transport service belongs affects the way in which that transport service is implemented. Figure 4-2 shows the five types of CSI, along with popular transports and VoIP transport services. Figure 4-2:CSIs with popular transports and transport services. As […]

How VoIP and the Internet Fit the CSI Picture

To understand how the Internet relates to the five CSIs, it helps to first recognize what the Internet is. No doubt Bell would be captivated by the enormity of what we call the Internet. By definition, it is a network of networks. But just like VoIP can run on any of the five CSIs in […]

Getting Switched (VOIP)

In This topic ^ Supporting VoIP over the PSTN ^ Controlling millions of calls ^ Understanding quality of service issues In previous topics, I discuss the beginnings of the public switched telephone network, or the PSTN. I also outline some history of the PSTN. Perhaps the most significant piece of history was the development and […]

Understanding How the PSTN Supports VoIP

No other network in the world can compare to the reliability of the U.S. switched network. (Granted, a handful of disasters have disrupted PSTN services in specific regions, but these are the exceptions, not the rule.) Such reliability, however, comes at a high price: The cost of the switched network, particularly recurring (per-minute) charges, is […]

Quality and VoIP

When we talk about various forms of telephone quality of service (QoS), it is understood in the industry that toll quality means the highest form of telephony service quality controlled by SS7. One of the largest problems with early VoIP was QoS. Connections could be made over the PSTN and into the Internet, but what […]

Controlling Calls (VOIP)

You might wonder how the PSTN manages to control millions of circuit-switched telephone calls each day. Most people know that their telephone connects to the public telephone network, but they don’t know what happens to make it work beyond that point. A critical part of the PSTN infrastructure is making each telephone call successful. To […]

Going Broadband (VOIP)

In This Topic ^ Transmitting over broadband ^ Setting up VoIP over cable ^ Setting up VoIP over DSL In the beginning, the only public access to the Internet was through slow, <C dialup modems, which had a typical maximum speed of 56 Kbps. During the 1990s, people clamored for higher-bandwidth alternatives. Much of the […]

Broadband Transmission Methods (VOIP)

Two types of transmission are used with both cable modem and DSL broadband services: asymmetric and symmetric. These transmission types are necessary to optimize and share bandwidth, which is more of a requirement in highly populated areas, where the lines can get congested. These two types are distinguished by the amount of bandwidth available to […]

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