ISDN is a digital connection used for voice calls and high-quality data links with other ISDN subscribers. ISDN can be used for transferring large files securely, video-conferencing and linking Local Area Networks at different sites. You can also make data calls to other countries that have ISDN services.
A single, high-quality, ISDN2e line has two 64k channels. Usually you’d use these separately, so you can make two calls at once. These could be two simultaneous voice calls, two data calls or one voice call and one data call.
You can also add more ISDN2e circuits to your installation, increasing the number of simultaneous connections and/or available data bandwidth.
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.
For help using IDSN2/2e, go to our Using ISDN2 and ISDN2e guide.
Use ISDN2e straight away
You can connect eight digital devices to a single ISDN2e circuit by plugging group four into either socket in your ISDN2e box.
Examples of digital devises you can use:
- digital telephones
- digital fax machines or
- computers equipped with an ISDN card or a Terminal Adapter
- analogue equipment, which you connect to the ISDN circuit through an interface called a Terminal Adapter.
Terminal Adapters are available from the BT Business Store. Make sure to check that your Internet Service Provider (ISP) supports digital access.
With a different line configuration, instead of connecting 8 digital devices you can connect a digital switch/PBX.
Before connecting a digital telephone system to ISDN2e, please check its documentation or consult the supplier.
Phone numbers
You can have separate phone numbers for telephones or other devices connected to your circuit. How you do this depends on your line configuration:
- If you connect devices directly to the circuit, you can have up to nine additional MSN phone numbers which you allocate to your equipment.
- If you use a switch/PBX, you can have an unlimited quantity of DDI numbers.
Exchange services
BT offers a range of digital exchange services for ISDN2e which provide advanced call-handling facilities.
Configuring your service in different ways
An ISDN2e line can be configured in two ways, depending on how you intend to use it:
Standard Access
System Access
Terminal Adapters
When installing a new ISDN Terminal Adapter, you’ll be asked to select a switch protocol and to enter a SPID number.
Switch protocol
SPID number
More help
More information on common queries:
Can I receive incoming faxes?
How can I tell if I have been disconnected from a call?
What is the line loss limit on ISDN2e?
What signalling type does ISDN2e use?
Can my alarm system run over my ISDN2e line?
How can I present a DDI number in place of my outgoing CLI?
I have a new ISDN line and my PBX maintainer needs only 4 digits sent. How can I get this changed?
Equipment
Help getting started with the ISDN box and connected equipment.
Understanding two switches on the underside of the ISDN box
Compatible PCs
Connecting LANs using ISDN2e
Using a digital switch/PBX
Extension wiring
Features and benefits of ISDN2e explained
Find out what features and benefits are available with ISDN2e.
BT Call Features available with ISDN2e
Keeping your outgoing number private
Caller ID on ISDN2e
Ceased Number Intercept (CNI) on ISDN2e
Remote Call Forward (RCF) on a ceased ISDN2e circuit
For more information on ISDN2/2e including how to use calling features, go to our Using ISDN and ISDN2e guide.
Support
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.
| Package | Reporting Days | Reporting Hours | Response Time |
| Standard | Monday to Friday | 9am to 5pm | 24 hours |
| Total | 7 days a week | 24 hours a day | 4 hours |