3com SuperStack 3 NBX Manual De Usuario

See 

 for further information on 

how to set up VTLs in the dial plan.

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.

 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 9   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 

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