Nortel Networks NN43001-563 - Manual (Page 66)

66 System description
North American dialing plan
The North American dialing plan is used to make public network calls
through the private IP network. However, calls are not directly routed to the
Central Office (CO) through the LAN connection. Instead, a tandem switch
with voice trunk connections, including T1 ISDN PRI, serves as the gateway
to route voice calls coming through the LAN to the voice trunk.
Figure 20 "North American dialing plan — call flow" (page 66) shows
DN 7000 placing a public call, through the private LAN, by dialing
1-415-456-1234 or 566-1234. The IP trunk card with IP address
47.82.32.124 searches for the Numbering Plan Area (NPA) or Local
Exchange Code (NXX) tables with the matched NPA or NXX entries. When
an entry is found, the corresponding IP address is used to send H.323 call
setup messages to the gateway (a Meridian 1/CS 1000M with an IP address
of 47.82.32.123), which routes the call to the PSTN through a regular CO
or DID trunk.
The translation table is expanded to allow extended, three-to six-digit NPA
codes. For example, DNs, such as 1-415-456-XXXX and 1-415-940-XXXX,
can have different destination IP addresses.
Figure 20
North American dialing plan call flow
Flexible Numbering Plan
A Flexible Numbering Plan (FNP) allows the length of Location Codes
(LOCs) to vary from node to node. As well, the total number of digits dialed
to reach a station can vary from station to station. It also allows flexibility for
the length of the location codes from node to node. An FNP can be used
to support country-specific dialing plans. FNP also allows users to dial
Nortel Communication Server 1000
IP Trunk Fundamentals
NN43001-563 01.01 Standard
Release 5.0 30 May 2007
Copyright © 2007, Nortel Networks
.