ISDN
From New Zealand VoIP Users Group
Integrated Services Digital Network
See Wikipedia
Basic Rate Interface
Basic Rate ISDN (BRI/BRA) is a digital connection consisting of two 64kbit/s channels (B channels) and one 16kdit/s channel (D channel) run over a normal copper phone line.
Both B channels can be used simultaneously, this means you make two calls (incoming or outgoing at once). The D channel is used for signalling (ringing, pickup/hangup, callerid, etc). Having a separate signalling channels allows more flexibility than an analog POTS line. You can do things like have 10 phone numbers (DIDs) assigned to your connection.
As at April 06 Telecom charges around $140 setup and $110 per month for a BRI ISDN connection. Number blocks (10) are $40 per month.
