Nortel ISDN Signaling Link, Описание, установка и эксплуатация

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Page 50 of 378 Description
553-3001-202 Standard 1.00 April 2000
For example, Meridian 1 switch B node B1 has two entries for NPA 408 and
4085 which point to nodes A1 and A2 of Meridian 1 switch A, respectively.
Calls from B1 with dialed digits 408-5xx-xxxx are routed to the ITG node A1
while all other 408-xxx-xxxx calls are routed to ITG node A2.
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 10 shows DN 7000 placing a public call, through the private LAN, by
dialing 1-415-456-1234 or 566-1234. The ITG ISL 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 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.