Can I use ISDN2e straight away?

Yes, you can plug Group 4 fax machines, ISDN phones and video-conferencing terminals into either socket in your ISDN2e box. Once configured, you can use these without any additional equipment.

To connect a computer you will need a correctly configured ISDN card or a Terminal Adapter. These are available from the BT Business Store. You should also check that your Internet Service Provider (ISP) supports digital access.

Before connecting a digital telephone system to ISDN2e, please check its documentation or consult the supplier.

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How many calls can I make at once?

Two. These could be two simultaneous voice calls, two data calls or one voice call and one data call.

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Can I receive incoming faxes?

Yes, provided your equipment and/or software supports ISDN connection and is correctly set up. Contact your supplier for advice.

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Can the service be configured in different ways?

Yes, an ISDN2e line can be configured in each of two ways, depending on how you intend to use it:

Standard Access (also known as S/T reference or Point to Multi-point)
The ISDN2e Standard Access configuration enables signals from the BT network to communicate directly with equipment you connect to your circuit, eg, your telephone or computer. Standard Access is the normal configuration for a single ISDN2e line. You can assign additional telephone numbers to individual devices using Multiple Subscriber Numbering (MSN).

System Access (also known as T reference or Point to Point)
System Access is required when you connect one or more ISDN2e lines to a switch/PBX. The signal from the network travels as far as the switch/PBX, which then determines where the calls are sent. If you have a switch/PBX, you can use Direct Dialling In (DDI) to associate telephone numbers with particular extensions.

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I've noticed two switches on the underside of the ISDN box. What are they for and what are the normal settings?

The settings for these switches depend on whether you have any digital extension wiring. One switch has two positions: 'IN' and 'OUT'. The other has two positions: 'S' and 'L'.

The setting for the 'IN' and 'OUT' switch depends on whether the electrical resistance at the furthest point of your ISDN wiring is inside or outside the ISDN2e box. If you connect your ISDN equipment directly to the sockets in the ISDN2e box without any extension wiring, this switch should be set to 'IN'. If you have digital extension wiring, the termination resistance will be at the final extension socket. The setting should therefore be 'OUT'.

The 'S' and 'L' switch setting depends on the length of any digital extension installed. It should be set to 'S' for extension wiring up to 150 metres, and 'L' for extension wiring between 150 and 800 metres in length.

In an ISDN2e installation with no digital extension wiring, the switches are set to 'IN' and 'S'.

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How many digital phones, computers and other devices can I attach to the line at once?

8, any 2 of which can be in use at the same time.

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Can I use my existing telephone equipment?

If you wish to use analogue phones, faxes, answering machines or modems, you will need an ISDN Terminal Adapter with analogue ports. You can buy adapters offering different features from the BT Business Shop.

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Can I make international ISDN calls?

Yes. You can take advantage of clear 64k paths to overseas destinations. These provide high transmission quality and low error rates. Applications include large-file transfer (e.g. photos, graphics and typesetting), database access, video-conferencing and distance learning.

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Are call charges the same as for normal analogue lines?

Charges for voice calls are the same as for analogue lines, as are data calls within the UK. There are different rates for international 64k data calls.

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What support does BT offer?

Our Standard Care package is provided as part of the ISDN2e service. You can opt for the Total Care package at an extra cost, through Business Sales on 0800 800 152.

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How can I tell if I have been disconnected from a call?

Most phone systems and Group 4 fax machines clearly indicate call status. To avoid paying for unintentionally extended calls, ensure that you understand the call-status display. Likewise, find out how your ISDN card or Terminal Adapter indicates call status.

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What is the line loss limit on ISDN2e?

The line loss for ISDN2e is 47 dB. The exact distance this represents depends on the type of cable, number of joints, etc, between the exchange and your premises. For this reason, ISDN installation is always subject to a preliminary survey.

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What signaling type does ISDN2e use?

ISDN2e uses the signaling protocol generically known as Q.931 or Euro-ISDN.

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Can my alarm system run over my ISDN2e line?

If your alarm system currently relies on a conventional telephone line, you may be able to connect it using an ISDN Terminal Adapter. You will need to check with your alarm company that your system is supported on ISDN connections.

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How can I present a DDI number in place of my outgoing CLI?

There is not an exchange-provided service. You need a PBX or switch that enables you to allocate each DDI number to a phone extension, so that incoming calls to DDIs are routed appropriately and have a corresponding number presentation.

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My computer is asking for a SPID number when I try to install an ISDN terminal adapter. What is my SPID number?

SPID numbers apply only to non-European (normally American) ISDN equipment. A card developed for the American market may ask you to enter a SPID during installation.

Equipment asking for a SPID number is not necessarily designed for use with ISDN in Europe and may be incompatible with ISDN2e.

First, confirm that the equipment has the ISDN protocol set to Euro-ISDN, DSS1 or NET3. If it does, it should not request a SPID. If it still requests a SPID, try leaving the key-in box empty or entering your phone number. Otherwise, contact the equipment supplier.

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I'm installing a new ISDN Terminal Adapter and have been asked to select a switch protocol from a list. Which do I choose?

For an ISDN2e line, you can select Euro-ISDN, DSS1 or NET3.

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I have a new ISDN line and my PBX maintainer needs only 4 digits sent. How can I get this changed?

By default, the exchange sends 6 digits down the ISDN line to your equipment. Just contact us and we’ll do it for you. You can either chat online with us, or call. Just click on Contact us on the right of this page.

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