Do telephones work with hearing aids?
A lot of telephones work in conjunction with inductive loop technology for the hard of hearing. We are able to retrofit this to certain types of telephone.
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What does Bandwidth mean?
The term used to describe the rated throughput capacity of a given network medium or protocol. The term is also used to describe the difference between the highest and lowest frequencies available for network signals...
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What is a protocol?
A protocol is a set of rules that specifies how two devices will create and maintain a logical communications path between them. Various standards bodies are involved in defining these protocols.
Groups such as the International Standards Organisation (ISO), American National Standards Institute (ANSI), Institute of Electrical and Electronic Engineers (IEEE), International Telecommunications Union (ITU) and the Electronic Industries Association (EIA) have worked together to standardise these protocols.
These standards are open which means they are not proprietary. A manufacturer can use the standards to develop products that should work with other manufacturers' products that are based on the same set of standards.
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What is ADSL
(Asymmetric Digital Subscriber Line) is a technology for transmitting
digital information at a high bandwidth on existing phone lines to homes and
businesses. Unlike regular dialup phone service, ADSL provides
continuously-available, "always on" connection. ADSL is asymmetric in that
it uses most of the channel to transmit downstream to the user and only a
small part to receive information from the user. ADSL simultaneously
accommodates analog (voice) information on the same line. ADSL is generally
offered at downstream data rates from 512 Kbps to about 6 Mbps
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What is Broadband?
A transmission method that multiplexes multiple independent signals onto one cable. In telecommunications terminology, any channel having a bandwidth greater than a voice grade channel (4 kHz). In LAN terminology, a coaxial cable on which analogue signalling is used. Also called wide-band. Contrast with baseband.
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What is ISDN
ISDN (Integrated Services Digital Network)
Communication protocol offered by telephone companies, that permits telephone networks to carry data, voice, and other source traffic
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What is ISO OSI Network Mode?
The ISO OSI Network Mode
The International Standards Organisation (ISO) Open System Interconnection (OSI) Seven Layer Reference Model, or 7 layer model for short, is a basic set of hardware and software standards. It defines seven layers of communication protocols for a network as shown here.
Layer Function
Performs network services like File Transfer and email
Handles format and code conversions for programs
Establishes and maintains sessions between application programs
Communication across the Network
Data routing across the Network
Controls access to the medium - divided into Media Access Control (MAC) and Logical Link Control (LLC)
Networking medium - cable, connectors and wireless
Starting from the bottom the layers are :-
1. PHYSICAL - defines the electrical and mechanical characteristics of the network interface, type of medium, the transmission method and the transmission rates available for the network. Wireless systems such as Bluetooth are included in this layer.
2. DATA LINK - defines how the network media is accessed, which protocols are used, the packaging/framing methods and the virtual circuit/connection methods.
3. NETWORK - controls the way in which addressing is accomplished between linked networks.
4. TRANSPORT - handles the task of reliable message delivery and flow control between applications on different stations.
5. SESSION - establishes two way communications between applications running on different stations on the network.
6. PRESENTATION - translates data formats so that computers, with different "languages", can communicate.
7. APPLICATION - interfaces directly with the application programs running on the station.
The OSI specification is most tightly defined in layers three and five, and widens out in both directions where at the extreme ends there are a wide variety of protocols acceptable to OSI. For instance at the physical layer there may be twisted pair, coaxial cable, optical fibre or wet string and at layer seven there are database, word processing and email applications.
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