Nortel Modular ICS 6.0 Installer's Manual page 105

Call-by-Call routing
Toronto office
Toronto Office
Network #: 2221
Rec'd #: 2221
Internal #: 2221
DID #: 763-2221
PRI
PRI
Central
Central
Office
Office
If call-by-call services were not used, each Norstar system
might have to be equipped with the following trunks:
• 12 DID lines needed to handle peak incoming call traffic.
• eight Tie (E&M) lines needed to handle inter-office calls.
• eight lines needed to handle outgoing public calls
The total required is 28 lines. If the Norstar systems were using
T1 trunks, then two T1 spans would be required at each office.
Note that the total of 28 lines represents the worst case value
for line usage. In reality, the total number of lines in use at any
one time will generally be less than 28. For example, during
periods of peak incoming call traffic, the demand for outgoing
lines will be low.
With PRI call-by-call services, it is not necessary to configure
a fixed allocation of trunks. Each of the 23 lines on the PRI can
be used for DID, Tie, or outgoing public calls. This
consolidation means that it may be possible for each office to
use a single PRI span, rather than two T1 spans.
P0992638 03
Network #: 2221
Rec'd #: 2221
Internal #: 2221
DID #: 763-2221
Tie connection
Tie Connection
Public network
Public Network
Dialing plans / 105
New York office
New York Office
Network #: 6221
Network #: 6221
Rec'd #: 6221
Rec'd #: 6221
Internal #: 6221
Internal #: 6221
DID #: 763-6221
DID #:562-6221
Central
Central
Office
Office
Modular ICS 6.0 Installer Guide
PRI
PRI