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Hitchhiker's Guide To Telephony
The world of telephony is big.  Really big.  You just won't believe how vastly, hugely, mind-bogglingly big it is.  I mean, you may think it's a long way down the road to the chemist's,but that's just peanuts compared to the world of telephony...

Stolen and mangled quotes aside, talking telecommunications is a second language to some; and as interesting as dried emulsion to others.

We talk it because it's our business and we've been in the business of telecommunications for over 20 years.

In that time we've fitted just about every sort of telephone system for small businesses upwards, and for all sorts of applications from moving a single socket to
installing the very latest IP based systems.

So here's our handy dandy guide to the world of telecommunications.

ADSL Stands for 'Asymmetric Digital Subscriber Line'. ADSL transforms the existing twisted copper pairs between the telephone exchange and the telephone socket into a high-speed digital line, allowing Broadband access. ADSL delivers fast download speeds but slow upload speed.

Analogue Line

Auto Attendant
An automated system designed to guide a caller through the options of a voice menu. Typically set to answer and route incoming calls.

The capacity of a telecom line to carry signals. The necessary bandwidth is the amount of spectrum required to transmit the signal without distortion or loss of information. FCC rules require suppression of the signal outside the band to prevent interference.

Stands for 'Basic Rate Interface' - see ISDN2e

A term used to describe fast internet access. Wide bandwidth which can be either ADSL or SDSL. ADSL can suffer from vast bandwidth changes (see also Contention Ratio).

Call Hold
A service feature that enables a user to retain an exisiting call, while accepting or originating another call using the same handset or phone device. The held call is tied to the handset that placed the call on hold and, therefore, can only be taken out of hold from the same handset.

Call Park
A service feature that allows a user to place an active call on 'hold' at one telephone handset and then retrieve the call, from any other handset within the same phone network. The call is effectively placed in a 'parking bay' and is allocated a parking bay number, e.g. 101. Users can then pick up another handset on the same network and type in the bay number to retrieve the held call.

Call Transfer
A service feature that allows a user to place a call on hold whilst, simultaneously, transfering the call to another destination. The detsination can typically be both an internal or external telephone.

Contention Ratio
A term used to describe the number of individual broadband customers connecting to a single internet node at the local public exchange. High contentions ratios will cause vast speed differences depending on time of day and number local users on line. Beware of the '4pm school rush'!

Historically, Voice & Data networks were kept entirely separate. However in recent years, changes in technology have meant that many businesses can now run both voice and data over the same LAN, thereby causing them to 'converge'. Cost savings are one benefit of Convergence but far more importantly there are significant productivity and efficiency gains to be achieved. VOIP, IP Telephony, Unified Messaging, Remote Working etc all come under the 'Convergence' umbrella.

Stands for 'Direct Dial Inbound' - allows users to rent individual phone numbers without the need to rent individual lines. DDI's are mapped onto specific ISDN lines and the PBX is then programmed to direct the incoming DDI call to the specific extension or hunt group as required. Customers can rent a large volume of DDI's whilst benefiting from renting an optimum number of lines based on required usage.

Stands for 'Digitally Enhanced Cordless Telecommunications'. A technology used to link cordless mobile handsets to a wired telephone system.

Stands for 'Direct Exchange Line' - see PSTN

A very common method of networking computers in a LAN. An 'Ethernet' describes the physical network that carries data traffic.

Exchange Line

A BT specific service running over the PSTN. Designed for small companies (typically max 3 users), it is a dated product that provides limited basic PBX functionality requiring one dedicated phone line per user. Featureline is not considered to be cost effective for 4 or more users.

Fibre To The Cabinet (FTTC)
This is a generic term for any broadband service that uses fibre optic cable, in place of traditional copper wiring, to connect a telephone exchange to the 'green cabinets' in the surrounding roads. This means that copper wires are only used in the last few hundred metres between a green cabinet and a customer's premises. Unlike copper, fibre does not suffer from signal loss over distance and so provides much faster download and upload bandwidth speeds.

Hosted Telephony / Hosted VoIP
What is Hosted Telephony?  (aka Hosted IP Telephony).
An IP based phone system that is "Hosted" in a data centre. Customer sites connect to the hosted phone system via an internet connection** that is generally either ADSL or SDSL but can be a leased line. All the intelligence of the phone system is held within the data centre and the on site equipment is controlled by the central system. Customer communication profiles are configured via a simple web based browser and individual users can control their own phone profile from any internet connection, with ease. Hosted Telephony is particularly beneficial for companies with two or more sites and can be used internationally. All calls made between customer sites are FREE.
** The quality of the internet connection is critically important and it is recommended to keep the voice and data on separate internet connections.

Hunt Group
Multiple phones allocated to a single DDI or extension number, thereby enabling an inbound call to be answered from any phone, within the allocated group of of phones. I.e. accounts or sales depts etc. Inbound calls can be configured to 'hunt' from one phone to another (until answered) or to be "broadcast" across all phones in the group, so they all ring at once.

Stands for 'Information and Communication Technology'. Equipment such as computers, the Internet, CD-ROMS and other software.

Stands for 'Internet Protocol'. A standardised method of transporting information across the Internet in packets of data. It is often linked to Transmission Control Protocol, which assembles the packets once they have been delivered to the intended location.

IP Telephony  (also see Hosted Telephony)
Using Internet Protocol as a method of carrying voice calls. With IP, voice communications (in the form of IP packets) are routed directly from the origin to destination devices.

ISDN (provided in two formats as per below)
Stands for 'Integrated Services Digital Network'. Digital telephony service that gives better call quality, quicker connection times and DDI facilities. ISDN is generally provided to connect to a customers PBX. ISDN can also be used in Radio and was historically used for faster Internet connection before the advent of broadband.

Provided in pairs i.e. 2 channels/lines per ISDN2e. The majority of customers would get a maximum of 4 pairs before moving up to ISDN30e. The e stands for the European standard.

Provided over one large circuit (bearer/pipe) either as copper or in many cases fibre optic. The minimum number of channels/lines one can have is 8 moving up to 30. Larger organisations can rent multiple ISDN30e's should they require more lines. The e stands for the European standard.

Stands for 'Local Area Network' - Data network that connects computers, servers, printers etc together, generally within one physical location.

Leased Line
Dedicated private internet access circuit - provides secure, fast and uncontended internet access.

Stands for 'Multi Protocol Label Switching' - A flexible and cost effective way of providing a WAN.

Public (Automated) Branch Exchange aka Switchboard aka Phone System.

Stands for 'Plain Old Telephone Service' - see PSTN

Stands for 'Primary Rate Interface' - see ISDN30e

Stands for 'Public Switched Telephone Network'. This is the standard telephone service provided over basic analogue phone lines.

A device (or, in some cases, software on a computer) that directs IP packets to the next point toward their destination.

Stands for 'Symetric Digital Subscriber Line'. The same as ASDL but provides the same speed/bandwidth in both directions. Useful for companies needing to upload high bandwith packets quickly. Common requirement with VOIP networks.

Stands for 'Session Initiation Protocol'. It is essentially a communications protocol used to set up and clear down sessions with one or more users over the internet.  Can be used in a multitude of scenarios, but most common is in the initiation  and termination of Voice over IP calls.

SIP Trunks
Basically an internet phone line.  Part of the broadband bandwidth is allocated solely for a VoIP call.  Each VoIP call requires one SIP trunk but a good quality broadband service can accommodate multiple SIP trunks.  SIP trunks are much cheaper to rent than traditional phone lines.

Stands for 'Service Level Agreement' - part of a service contract where the level of service is formally defined. In practice, the term SLA is sometimes used to refer to the contracted delivery time (of the service) or performance.

Stands for 'Simple Mail Transfer Protocol'. The standard Internet protocol for transferring electronic mail from one computer to another.

Unified Messaging[/color]
Enables you to access voice, fax, and text messages via one single email or telephone account.

Stands for 'Virtual Private Network' - A way of creating a private communications network over a public network (mostly the internet) using secure protocols (passwords, authentication methods etc).

VOIP  (see Hosted Telephony)
Stands for 'Voice Over Internet Protocol' - Voice translated into data packets and transmitted across an internet connection or network - just like any other file or email you might send. Upon reaching the other end data is transformed back into its original form and emerges like a regular phone call. (VOIP is critically dependent upon the speed of the packets across the internet and the correct assembly order once they arrive at their destination _for obvious reasons!)

Stands for 'Wide Area Network' - Connects multiple LAN's together, typically via VPN's over broadband and/or Leased Lines - (The Internet is actually a WAN itself)

PSTN Select Services

Anonymous Call Rejection
Rejects calls where the caller withholds their number.

Answer 1571
Takes messages for you when you are unavailable or your line is engaged.

Bar Use of Call Return
Means callers to your number cannot use the Call Return option (i.e. pressing '5' if you are engaged so that it calls them back)

Call Barring
Stops certain calls being made from your phone.

Call Diversion
Allows you to divert calls to almost any phone - anywhere in the UK, most overseas destinations or a mobile phone!

Call Minder
Like Answer 1571, with the additional advantage of remote access and the option of having personalised messages.

Call Return
A service that will call your phone to let you know when an engaged number becomes free.  Normally activated by pressing '5' when you reach an engaged number.

Call Sign
Allows you to distinguish between incoming calls on the same line.

Call Waiting
Tells you if someone is trying to call when you're already on the phone.

Caller Display
Displays the number calling you

Caller Redirect (CNI)
A recorded announcement on a ceased line advising the caller of the new number to dial.  This is a chargeable service.

Choose to refuse
Enables you to bar the telephone number of the last answered incoming call.

Presentation Number
Enables the option of "masking" the main outbound number of a telephone line with a different number. This option is seful for call centres or companies that are located in obscure locations and dont want end users to know their physical location or if they want to present a non-geographic number to the customers they are calling. For example, a company has a simple 0207 number but they want an 0845 number to be displayed to every end user that they call.

Pulse Metering
Sends 50Hz pulses to customers' lines to indicate units of charge.

Reminder Call
An alarm call that you are able to set up by programming your own phone.

Remote Call Forwarding (RCF)
A method for forwarding calls made to a ceased line to a new number, without the caller being aware that the call has been forwarded.  There is normally a set up cost and monthly charge for this service.  In addition the owner of the line has to pay the cost of the forwarded part of the call, as well as the exchange line rental for the ceased line (this is because the number of the ceased line cannot be reallocated to another user whilst RCF is in effect)

Ring Back
See 'Call Return'

Smart Divert[/color]
Call divert with remote access

Three Way Calling
Allows you talk to two people at the same time - even if one of them is abroad!

ISDN Select Services

Call Barring
Stops certain calls being made from your phone.

Call Deflection
Enables incoming calls to be identified and then forwarded to another destination before answering the call. Alternatively, incoming calls can be automatically forwarded to selected destinations dependent on their calling line identity.

Call Forwarding
Automatically transfers incoming calls to a different location, e.g. if moved to a different exchange area. Can either be admin provided or customer controlled.

Calling Line Identity Restriction (CLIR)
This prevents your directory number from being released at any time.  It is useful if you don't want people to call you back, i.e. if you are running an outbound telemarketing campaign.

Calling Line Identity Presentation (CLIP)
Lets you see the number of the person calling before you pick up the phone, enabling you to greet the caller in an appropriate manner.

Connected Line Identity Presentation (COLP)
Allows you to see the number of the line that you have been connected to.

Connected Line Identity Restriction (COLR)
Restricts the access of incoming callers to your identity

Presentation Number
Enables the option of "masking" the main outbound number of a telephone line with a different number. This option is useful for call centres or companies that are located in obscure locations and dont want end users to know their physical location or if they want to present a non-geographic number to the customers they are calling. For example, a company has a simple 0207 number but they want an 0845 number to be displayed to every end user that they call.
Page Telecommunications Limited is a privately owned company registered in England. Registered Number: 4846013
Created by J Harrowell.      © 2013 Page Telecommunications Limited, All Rights Reserved.