Jargon Buster

Jargon Buster

ADSL - Asymmetric Digital Subscriber Line
Essentially this is your standard broadband line

CLIP - Caller Line ID Presentation
The Digital version of Caller Display

CLIR - Caller Line ID Restriction
This gives you the ability to restrict your telephone number on outgoing calls

Contended line
This means that you effectively share your internet connection with other users

DDI - Direct Dial Inward
A direct dial is used on digital lines (ISDN2e & ISDN30), through a telephone system allowing individuals to have direct numbers.

Dedicated connectivity
Your internet connection is just that – yours! You don’t share it with any other user.

EFM - Ethernet in the First Mile
In very simple terms, a copper version of the leased line, allowing businesses to get the same upload and download speed and a much faster connection that standard ADSL.

FTTC - Fibre to the Cabinet
Essentially known as 'Super Fast Broadband'.

FTTP - Fibre to the Premises
Another service like FTTC, however providing quicker speeds. Fibre runs to your premises rather than the BT Green Box

ISDN2e - Integrated Services Digital Network
A digital line, mostly used for businesses with a telephone system. This type of line comes in pairs and generally between 2 and 6 lines.

ISDN30e - Integrated Services Digital Network
Another type of digital line, generally used with Telephone Systems. You have to have a minimum of 8 channels with this option.

LAN - Local Area Network
More of an IT term, but this is your local network of computers, routers etc

NTE - Network Termination Equipment
The BT socket in most cases, it is essentially where you plug your equipment into the network, could be a phone or router for example


PSTN - Public Switched Telephone Network
A standard line also commonly referred to as a analogue line. You would have this at home or for your ADSL connection for example.


SIP - Session Initiation Protocol (Still doesnt make much sense does it)
In most basic terms, calls over the internet but unlike VoIP you need hardware onsite to manage incoming and outgoing calls.

SLA - Service Level Agreement
Not all products have service level agreements, make sure you understand what SLA's are included in any contract you agree.

SNDDI - Single Number DDI
Exactly as per DDI, however hence the name, it is a single number rather than a block you would normally associate with DDI.


Small and sometimes noisy, used to communicate across long distances.


VoIP - Voice Over Internet Protocol
Giving you the ability to make calls over the internet. No need for onsite hardware - other than a phone obviously.


WAN - Wide Area Network
Your connection to the outside world or your other offices