90 CHAPTER 2: DIAL PLAN
VTL Connections
Using Site Codes
The simpler way to implement VTL connections uses a site code,
consisting of one or more digits that a user must dial to specify the site
that is being called. This approach requires no restriction on the
telephone extension ranges, but does require the caller to dial the site
code digits as well as the extension.
A site code can by any number of digits you want, but typically, one- or
two-digit numbers make the most sense. The dial plan at each site must
include appropriate routing instructions for each of the possible site code.
Figure 29
shows three sites connected by VTLs. All sites use the same
range of extension numbers (1000 through 3999). To reach someone on
another NBX system, a user must dial a site code (61, 62, or 63 in this
example) followed by an extension.
Figure 29 Virtual Tie Lines Using Site Codes
To call someone in Atlanta, a user in Chicago must dial the site code 62
and then the appropriate extension (1000 through 3999). To reach a user
in Dallas, a user in Chicago must dial 63 and then the appropriate
extension (1000 through 3999). Because the extension is preceded by the
site code, there is no conflict between the extension dialed and an
identical extension number at the local site (Chicago). The choice of site
codes is made by the person who configures the dial plans for the sites.
See “Dial Plan Configuration”
later in this chapter for more information
on how to set up VTLs in the dial plan.
WAN
Chicago
NBX System
Extensions
1000 – 3999
Atlanta
NBX System
Extensions
1000 – 3999
Dallas
NBX System
Extensions
1000–3999
Site Code 61
Site Code 63
Site Code 62
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