Specifications

2-24
Reference Guide
Model No.
Running Head
ISDN Primary Rate Interface (PRI) Server Applications
(NFAS). The system is limited to 8 WAN links. Thus the system limit for NFAS is 191B+D
in T1 environments (8 times 24 minus 1 D channel) and 239B+D in E1 environments (8 times
30 minus 1).
Although this integrated access system supports NFAS, it can only be implemented within
private networks or in public networks where it is supported by the service provider. Within
EC and EFTA countries NFAS is considered an EC-MOU2 supplementary service which is
still at the discussion stage and therefore is not supported by any of the European Service
Providers.
Remote Login
In addition to carrying ISDN signaling information, the D channel can also be used to log into
a remote system unit to check card status, and perform necessary system maintenance. This
unique application does not require B channel allocation. The ISDN call is placed on the D
channel to the ISDN network and routed to the D channel of the remote unit. Coordination
with the ISDN facility provider is necessary to obtain the number for the remote system unit.
Applications
The ISDN PRI Server card can be used in a variety of applications:
•
Fractional ISDN PRI provisioning
•
Video conferencing
•
Integrated ISDN access with SINA
•
Video Broadcast
•
Router with redundant trunk routing via ISDN
•
Router adding incremental bandwidth
•
PRI to FXS
2.6.2 Fractional PRI Provisioning
An integrated access system equipped with a 8840C PRI Server card is used to groom multiple
fractional PRI circuits into one or more PRI circuits for backhaul to an ISDN switch. Perhaps
a customer may not need the entire bandwidth delivered by a PRI circuit. The optimal
alternative would be to purchase a fractional PRI service delivered over a regular T1 or E1
circuit. When a service provider has multiple fractional PRI customers, the service provider
can deploy the integrated access system to groom the multiple fractional PRI circuits into one
fully utilized PRI T1/E1 circuit which is back hauled to the switch. This concentration of PRI
circuits reduced back haul costs for the service provider, and conserves T1/E1 ports and
D-channels on the ISDN switch itself.