Cable telephony

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Cable telephony is a form of digital telephony over cable TV type networks. A telephone interface installed at the customer's premises converting analog signals from the customer's in-home wiring to a digital signal, which is then sent over the cable connection to the company's Cable television headend switching center. The signal is then sent on to the public switched telephone network (PSTN). Cable telephone provides another revenue stream for cable television system operators and gives the consumer the convenience of combing several services on a single bill - such as paid television, internet and telephone services. [1] At times in the industry this is referred to as "triple play".

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Emergency calls

The biggest obstacle to cable telephone service is the need for nearly 100% reliable service for emergency calls. PacketCable, one of the emerging standards being developed for digital cable telephony, seems to be the most promising and able to work with the quality of service demands of traditional analog telephone service.

Advantage

The biggest advantage to digital cable telephone service is similar to the advantage of digital cable television, namely that data can be compressed, resulting in much less bandwidth used than a dedicated analog circuit-switched service. Other advantages include better voice quality and perhaps future integration to a VoIP network providing cheap or unlimited nationwide and international calling. In most cases, digital cable telephone service is separate from broadband Internet access service being offered by many cable companies and does not rely on IP traffic or the Internet.

Disadvantage

One possible disadvantage to digital cable telephone service is similar to a disadvantage of cable Internet access, namely that the medium is shared, which could result in occasional delays and drops when high volumes of bandwidth are used or in some cases shared with entire neighborhoods. These delays could be experienced during the "prime time" parts of the day, when heavy Internet usage and Internet streaming devices can make telephone calls on this system difficult. However, by utilizing Cable Lab's Packet Cable interface specifications, cable operators are able to diminish the effects of heavy internet usage on call quality. This is done by way of QoS provisions present in the Packet Cable specifications. [2]

The second disadvantage it that this service requires power at the subscriber's end. In an emergency, if mains power is lost and without the battery backup unit provided at an additional cost by the cable provider, this telephone service ceases to function. Traditional landline service from phone companies supply phantom power over the communication wires and therefore keep attached devices operational.

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<span class="mw-page-title-main">Cable television</span> Television content transmitted via signals on coaxial cable

Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with broadcast television, in which the television signal is transmitted over-the-air by radio waves and received by a television antenna ; or satellite television, in which the television signal is transmitted over-the-air by radio waves from a communications satellite and received by a satellite dish on the roof. FM radio programming, high-speed Internet, telephone services, and similar non-television services may also be provided through these cables. Analog television was standard in the 20th century, but since the 2000s, cable systems have been upgraded to digital cable operation.

<span class="mw-page-title-main">ISDN</span> Set of digital telephony standards

Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Work on the standard began in 1980 at Bell Labs and was formally standardized in 1988 in the CCITT "Red Book". By the time the standard was released, newer networking systems with much greater speeds were available, and ISDN saw relatively little uptake in the wider market. One estimate suggests ISDN use peaked at a worldwide total of 25 million subscribers at a time when 1.3 billion analog lines were in use. ISDN has largely been replaced with digital subscriber line (DSL) systems of much higher performance.

Circuit switching is a method of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the communication session. The circuit functions as if the nodes were physically connected as with an electrical circuit.

Telephony is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone.

<span class="mw-page-title-main">Cable modem</span> Broadband Internet access device

A cable modem is a type of network bridge that provides bi-directional data communication via radio frequency channels on a hybrid fibre-coaxial (HFC), radio frequency over glass (RFoG) and coaxial cable infrastructure. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high bandwidth of a HFC and RFoG network. They are commonly deployed in the Americas, Asia, Australia, and Europe.

Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for voice calls for the delivery of voice communication sessions over Internet Protocol (IP) networks, such as the Internet.

Plain Old Telephone Service (POTS), or Plain Ordinary Telephone System, is a retronym for voice-grade telephone service employing analog signal transmission over copper loops. Originally POTS stood for Post Office Telephone Service as early phone lines in most parts of the world were operated directly by the local Post Office.

<span class="mw-page-title-main">DSLAM</span> Network device that connects DSL interfaces to a digital communications channel

A digital subscriber line access multiplexer is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques. Its cable internet (DOCSIS) counterpart is the cable modem termination system.

The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists of telephone lines, fiber-optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables interconnected by switching centers, such as central offices, network tandems, and international gateways, which allow telephone users to communicate with each other.

A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by businesses to connect geographically distant offices.

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<span class="mw-page-title-main">Business telephone system</span> Telephone system typically used in business environments

A business telephone system is a telephone system typically used in business environments, encompassing the range of technology from the key telephone system (KTS) to the private branch exchange (PBX).

<span class="mw-page-title-main">Internet Protocol television</span> Television transmitted over a computer network

Internet Protocol television (IPTV), also called TV over broadband, is the service delivery of television over Internet Protocol (IP) networks. Usually sold and run by a telecom provider, it consists of broadcast live television that is streamed over the Internet (multicast) — in contrast to delivery through traditional terrestrial, satellite, and cable transmission formats — as well as video on demand services for watching or replaying content (unicast).

<span class="mw-page-title-main">Passive optical network</span> Technology used to provide broadband to the end consumer via fiber

A passive optical network (PON) is a fiber-optic telecommunications network that uses only unpowered devices to carry signals, as opposed to electronic equipment. In practice, PONs are typically used for the last mile between Internet service providers (ISP) and their customers. In this use, a PON has a point-to-multipoint topology in which an ISP uses a single device to serve many end-user sites using a system such as 10G-PON or GPON. In this one-to-many topology, a single fiber serving many sites branches into multiple fibers through a passive splitter, and those fibers can each serve multiple sites through further splitters. The light from the ISP is divided through the splitters to reach all the customer sites, and light from the customer sites is combined into the single fiber. Many fiber ISPs prefer this system.

PacketCable network is a technology specification defined by the industry consortium CableLabs for using Internet Protocol (IP) networks to deliver multimedia services, such as IP telephony, conferencing, and interactive gaming on a cable television infrastructure.

<span class="mw-page-title-main">Triple play (telecommunications)</span> Bundling of television, internet, and telephone service

In the field of telecommunications, the concept of triple play service refers to the provision of three essential services — high-speed broadband Internet access, television, and latency-sensitive telephone services — all delivered over a single broadband connection. This approach emphasizes the convergence of multiple services by a single supplier, aiming to enhance user convenience and streamline service delivery.

In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband internet access which uses the same infrastructure as cable television. Like digital subscriber line and fiber to the premises services, cable Internet access provides network edge connectivity from the Internet service provider to an end user. It is integrated into the cable television infrastructure analogously to DSL which uses the existing telephone network. Cable TV networks and telecommunications networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, mobile networks and satellite internet access.

The following outline is provided as an overview of and topical guide to telecommunication:

A managed facilities-based voice network (MFVN) is a communications network managed, operated, and maintained by a voice service provider that delivers traditional telephone service via a loop start analog telephone interface. MFVNs are interconnected with the public switched telephone network (PSTN) or other MFVNs and provide dialtone to end users. Historically, this was provided by equipment at Bell company central offices, however today's MFVNs can include a combination of access network, battery-backed customer premises equipment (CPE), network switches and routers, network management systems, voice call servers, and gateways to the broader PSTN.

<span class="mw-page-title-main">Modem</span> Device that modulates an analog carrier signal to encode digital information

A modulator-demodulator or most commonly referred to as modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by modulating one or more carrier wave signals to encode digital information, while the receiver demodulates the signal to recreate the original digital information. The goal is to produce a signal that can be transmitted easily and decoded reliably. Modems can be used with almost any means of transmitting analog signals, from light-emitting diodes to radio.

References

  1. Richard Grigonis (ed) Cable Telephony in Computer Telephony Encyclopedia, Focal Press, 2000 pp.68-69
  2. , PacketCable™ Dynamic Quality-of-Service Specification.