Instruction manual

System Features
Integrated Services Digital Network (ISDN) (DK40i, DK424i only)
Strata DK General Description 6/00 79
ISDN Primary Rate Interface (PRI)
PRI is the larger ISDN interface (via the RPTU) and uses the 23B+D transmission format, which
has 23 64-kbps bearer channels and one 64-kbps data (control) channel, with total bandwidth of
1.544 mbps.
PRI is designed as the trunk interface to the ISDN network. PRI connects the DK40i or DK424i
telephone system to an intra- or inter-LATA communication provider. PRI can be used to send/
receive voice and/or data.
More importantly, PRI can save money by enabling the multiple use of the channels on the PRI
link for a variety of services, such as DID, Tie, FX, WATS, 800, etc., on demand.
This capability to support multiple services and dynamically allocate channel use as needed is
known as the call-by-call feature. PRI lines also support Calling Number Identification Services
(CNIS).
A dealer-supplied, UL listed, Channel Service Unit (CSU) is required between the DK PRI
interface and the PRI line provider interface in most locations of the U.S. In Canada, a CSA
certified DSU/CSU must be installed.
ISDN Basic Rate Interface (BRI)
Strata DK40i and DK424i support BRI S/T features. As of Release 4.3 and higher, Strata DK40i
and DK424i support BRI U basic features.
BRI is the smaller ISDN interface and provides two simultaneous voice or data connections with a
single interface. BRI uses the 2B+D transmission format which is defined as two 64-kbps bearer
channels and one 16 kbps data (control) channel. The D-channel carries call setup control data.
ISDN BRI station applications allow the connection of ISDN instruments, such as a group IV fax,
PC, computer terminal or port, a LAN bridge, video conferencing terminal, Internet access
devices, LAN access routers, or other devices that benefit from an all digital transmission link.
BRI applications for the DK424i will include video conferencing, remote access servers, faster
Internet access, point-of-sale devices and high-speed data connections from ISDN stations to the
public ISDN network, as well as typical voice and fax connections. With the correct external
adapter, data can be sent up to 128 kbps.
Like PRI, BRI provides CNIS, DID, Direct Inward Lines, and other data access services when
used to access the public network.
The Strata DK BRI cards support both station side and trunk side connections. The Strata DK
systems also support BRI interface from the public network as a CO line service. There are two
types of ISDN BRI interfaces: S/T type (via RBSU/RBSS) and the U-type (via RBUU/RBUS for
DK40i and DK424i; TBUU/TBUS for DK40i). Both S/T and U types are used in the U.S.
The Public Switched Telephone Network provides BRI U-type lines only; therefore, a dealer-
supplied, external Network Terminal Unit (NT-1) is required to connect DK S/T-type BRI line
circuits to the network. The NT-1 must be UL listed (U.S.) or CSA certified (Canada).
Call-by-Call Service Selection
This feature permits the grouping of individual PRI B-channels to be shared among various types
of services specified by the customer, instead of having to dedicate each channel to a particular
type of service. Using this common pool of channels provides much improved traffic handling
than using dedicated channels.
This dynamic allocation of service can reduce the number of circuits required to access various
services, especially if various services have different peak busy periods.