A single, high-quality, ISDN2e line has two 64k channels. In normal operation you use these separately, so you can make two calls at once. You can add further ISDN2e circuits to your installation, increasing the number of simultaneous connections and/or available data bandwidth.
If required, 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 9 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.
BT offers a range of digital exchange services for ISDN2e which provide advanced call-handling facilities.
You can connect up to 8 digital devices to a single ISDN2e circuit. These can be digital telephones, digital fax machines or computers equipped with an ISDN card. You can also use analogue equipment, which you connect to the ISDN circuit through an interface called a Terminal Adapter.
With a different line configuration, instead of connecting 8 digital devices you can connect a digital switch/PBX.
You can use ISDN for voice calls and for high-quality data links with other ISDN subscribers. Digital connections are is often 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.