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glossary of terms

Business landline glossary of terms


Anonymous call reject

Anonymous call reject allows you to bar all anonymous callers who choose to withhold their phone numbers, such as unsolicited sales people.

Call back when line is free

If you've called an engaged line, a call back service will monitor the engaged line without you needing to call back. Once you hear an engaged tone, engage the service (usually by pressing a button on the keypad) and the network will monitor the busy line until it is free. Then your phone will ring to let you know the line is free and you can connect directly to the caller.

Call barring

If you want to restrict the outgoing calls that can be made from your business line, you can choose to block a range of call types. These could include international calls, mobile phones or premium rate services, for example.

Call divert

Call diverting sends your incoming calls to a different number - this could be your mobile phone, for example. Call diverting is a really useful feature if you're regularly on the move but still want a fixed business phone line and phone number.

Call waiting

Call waiting will alert you if you're using your business phone line and another customer calls through.

Caller display

With caller display, you can find out who is calling you before you pick the phone. If your phone handsets have displays on them, you'll be able to see the number of the person calling you before you answer the phone.

Carrier Pre-Select (CPS)

Carrier pre-select allows phone companies to use existing phone lines, previously owned by an incumbent supplier such as BT, for their own customers' use.


Centrex is a business telephone solution which is full managed at the telephone exchange of the telecoms supplier offering the package. This should allow you to avoid the cost and difficultly of managing a phone system yourself.


Having a conference service on your phone line will enable you to have multiple people on one call at the same time. This is particularly useful if you have a mobile workforce and could save you a fortune on travelling costs!


ISDN is an Integrated Services Digital Network (ISDN), which allows customer to transfer data, voice, internet applications and video conferencing without needing a modem.


ISDN2 is the most popular choice of connection for users with between 2 and 8 business phone lines.


ISDN30 is the most popular choice of connection for users with up to 30 business phone lines.

Reminder call

If you need to remind yourself of important appointments, some providers allow you to set a reminder call using their service. Never forget an appointment again - simply set the time and date you want the reminder call to be made and set the message you'll hear on the call.

Voice Over Internet Protocol (VOIP)

VOIP refers to the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks like the internet. As VoIP allows phone calls to be made via the internet, you could save a lot of money by implementing this technology.


Voicemail allows callers to leave you a recorded message when you can't make it to the phone.

Wholesale line rental (WLR)

WLR allows you to transfer the ownership of your phone lines to an alternative telecoms provider, allowing that provider to give you a single bill that covers both calls and line rental. This is more convenient for you and often leads to a reduction in bills.

Withhold number

You can choose to withhold your number on a call-by-call basis or, if you prefer, on all outgoing calls.