Vodavi Starplus Triad 1/2/3 Installation Manual page 72

CO/PBX Connections 2-51
Electronic Key Telephone Service
Electronic key telephone service (EKTS) is a feature that can be provided
on BRI ISDN to simulate standard analog DID lines. This allows several
different numbers to be shared by a single BRI circuit.
Due to the decline in telephony tariffs, there is an increasing demand for
BRI ISDN features. A BRI circuit allows two simultaneous calls to be
handled, due to its technical specification. BRI circuits have two
B-Channels at 64 kilobytes per second and one D-Channel at 16 kilobytes
per second. The Bearer (B) Channels are designed for PCM (voice) and the
Data (D) Channel is designed to carry information specific to each
incoming and/or outgoing call.
The EKTS feature allows a single ISDN Service Profile Identifier (SPID) or
B-Channel to support multiple directory numbers. A SPID is a number
that telephone company switching equipment uses to track
configuration information for each terminal adapter connected to an
ISDN telephone line. The telephone company should provide SPIDs at
the same time that the ISDN directory numbers are assigned. A directory
number is another term for a telephone number.
If an application requires EKTS, be aware that BRI ISDN handles a busy
number differently than a DID circuit. When the called number is busy,
BRI will issue a busy signal, but a DID circuit will ring another line in the
circuit. The busy signal is provided by the telephone company, therefore
the call is not presented to the Vodavi telephone switch and it is not
forwarded to voice mail. For example, a caller dials 480-443-6000 and is
connected to the extension. While the first caller is still connected, a
second caller dials the same number. The second caller will receive a busy
signal that is provided by the telephone company.
In a normal BRI application, two numbers are assigned to each BRI circuit,
which consists of 2 channels. There can be a maximum of 4 circuits
equipped to handle 8 channels per BRIB. This is a direct number-to-
channel relationship without hunting capability. Most circuit providers
offer an optional "hunting" feature capability on BRI circuits. This optional
feature allows numbers to hunt for idle channels on the BRIB up to a
maximum of 8 channels per BRIB, assuming four BRI circuits were
installed. In EKTS applications, you can have a maximum of 64 DID
numbers hunt to one BRIB. Hunting cannot be accomplished between
BRIBs, nor will the hunting feature allow calls to be routed to a busy DID
number.