Configuring a working VTL connection between two systems involves:
■ License Installation ■ Dial Plan Configuration ■ Updating the Extension List
■ Adding VTL Devices to the Pretranslators (Optional) ■ Verification of the Virtual Tie Line
You can enable silence suppression and different levels of audio compression for your VTL calls. For more information on how silence suppression and compression affect bandwidth, see “Audio Settings” on
page 257. To change the system-wide settings for silence suppression and compression on VTL calls, use the NBX NetSet utility to edit the audio settings: System Configuration > System Settings > Audio Settings. License Installation ■ You must obtain and install a license to enable VTLs.
■ Each VTL license applies only to the NBX system on which it is
installed. To connect three sites by VTLs and to have each site support up to 8 simultaneous active VTL connections, you must install a separate license key for 8 VTLs on each of the three NBX systems.
■ To increase the number of VTLs above one of the levels on a system,
you must add one or more incremental licenses of 2 VTLs each. To install a VTL license:
1 In the NBX NetSet - Main Menu window, click Operations. Click the Licenses tab and the Add License button. In the text boxes, type the license key code.
2 Click OK and then restart the NBX system. Dial Plan
Configuration
You configure the dial plan after you install the VTL license. See “License Installation” on page 89 for information about VTL licenses.
To configure the dial plan for VTLs, you must define:
■ Routes within the dial plan
■ Digit sequences to be used to select those routes ■ Operations to be performed for each route
Example: Dial Plan with Site-Unique Extensions
In Figure 10, each of the three sites uses a unique extension range. In the Internal table in the Chicago system dial plan, the entries shown in
Figure 12 control the routing of calls if a user dials an extension in the 2000 through 2999 range (Atlanta extensions) or the 3000 through 3999 range (Dallas extensions) respectively. The dial plans for the Atlanta and Dallas NBX systems would contain similar, but not identical entries. An explanation of each line in the dial plan follows Figure 12.
How to Configure a Virtual Tie Line 91
Figure 12 Sample Dial Plan Entries for Chicago Using Site-Unique Extensions
The first TableEntry Create command modifies entry 3 in Table 1. Entry 3 watches for 4-digit sequences (Min = 4, Max = 4) beginning with 2 (extensions 2000 through 2999) and specifies route 522 whenever a 4-digit sequence falls within this range. Entry 4 watches for 4-digit sequences (Min = 4, Max = 4) beginning with 3 (extension 3000 through 3999) and specifies route 523 whenever a 4-digit sequence falls within this range. Route numbers 522 and 523 are examples only. The choice of route numbers is made by the person who configures the dial plans for the sites.
Two DestinationRoute Create commands create routes 522 and 523. The Description field contains any text you want to use to describe each route.
Two DestinationRouteEntry Create commands specify the extension list for routes 522 and 523. Extension list *0006 is reserved for VTLs.
Table Create 1 Internal 4 Digit Extensions
/ Id Entry Digits Min Max Class Prio Route / -- --- --- --- --- --- ---- --- TableEntry Create 1 3 2 4 4 WAN 0 522 TableEntry Create 1 4 3 4 4 WAN 0 523
/ Route Description / --- ---
DestinationRoute Create 522 Atlanta VTL Connection DestinationRoute Create 523 Dallas VTL Connection
/ Route Entry DestinationExtension / --- --- --- DestinationRouteEntry Create 522 1 *0006
DestinationRouteEntry Create 523 1 *0006
/ Route Entry OperId Operation Value / --- --- --- --- ---
DestinationRouteOperation Create 522 1 1 prepend 192*168*25*100* DestinationRouteOperation Create 523 1 1 prepend 192*168*35*100*
Two DestinationRouteOperation Create commands prepend the IP Address of the destination NBX system to the extension that the user dialed. In this example, the IP address for Atlanta is 192.168.25.100 and for Dallas, the IP address is 192.168.35.100. You must use the asterisk (*) character to separate fields within the IP address and to separate the IP address from the destination extension.
Example: Dial Plan with Site Codes
In Figure 11, each of the three sites uses the same extension range. In the Internal table in the Chicago system dial plan, the entries shown in
Figure 13 select route 522 and 523 if a user dials the site codes 62 and 63 respectively, and then dials an extension. The dial plans for the Atlanta and Dallas NBX systems would contain similar, but not identical entries. An explanation of each line in the dial plan follows Figure 13.
Figure 13 Sample Dial Plan Entries for Chicago Using Site Codes Table Create 1 Internal 4 Digit Extensions
/ Id Entry Digits Min Max Class Prio Route / -- --- --- --- --- --- ---- --- TableEntry Create 1 100 62 6 6 WAN 0 522 TableEntry Create 1 101 63 6 6 WAN 0 523
/ Route Description / --- ---
DestinationRoute Create 522 Atlanta VTL Connection DestinationRoute Create 523 Dallas VTL Connection
/ Route Entry DestinationExtension / --- --- --- DestinationRouteEntry Create 522 1 *0006
DestinationRouteEntry Create 523 1 *0006
/ Route Entry OperId Operation Value / --- --- --- --- --- DestinationRouteOperation Create 522 1 1 stripLead 2
How to Configure a Virtual Tie Line 93
The first TableEntry Create command creates entry 100 in Table 1. This assumes that the highest previous entry in Table 1 was 99 or lower. Entry 100 watches for the 2-digit sequence 62 followed by a 4-digit extension and specifies route 522 whenever a user dials such a 6-digit (Min = 6 and Max = 6) sequence. Entry 101 watches for the 2-digit sequence 63 followed by a 4-digit extension and specifies route 523 whenever a user dials such a 6-digit sequence. The choice of route numbers is made by the person configuring the dial plans for the sites.
Two DestinationRoute Create commands create routes 522 and 523. The Description field contains any text you want to use to describe each route.
Two DestinationRouteEntry Create commands specify the extension list for routes 522 and 523. Extension list *0006 is the default extension list for VTLs.
For each DestinationRoute, two DestinationRouteOperation Create commands perform two functions:
■ The stripLead command removes the two digits (62 or 63) leaving the
4-digit extension the user dialed.
■ The prepend command adds the IP Address of the destination NBX
system to the extension that the user dialed. In this example, the IP address for Atlanta is 192.168.25.100 and for Dallas, the IP address is 192.168.35.100. In the dial plan, you must use an asterisk (*) instead of a period (.) to separate the fields within the IP address, and to separate the IP address from the destination extension.
Updating the Extension List
The final step in activating the virtual tie lines is to add the VTL extensions to the appropriate extension list (*0006).
To update the extension list:
1 In the NBX NetSet - Main Menu window, click Dial Plan. 2 Click the Extension Lists tab.
3 Select the Virtual Tie Lines extension list (*0006). 4 Click Modify.
5 In Extensions not in List, scroll down until you see the first VTL item. The number of VTL items depends on the VTL license you have.
Each VTL item has (VTL) at the beginning of the line, followed by the name of the virtual tie line.
Table 20 describes the VTL extension ranges.
6 Select the first VTL, and click << to move the VTL to Extensions in List. 7 Repeat until all VTLs are moved to Extensions in List.
o
Adding VTL Devices to the Pretranslators (Optional)
If you optionally added a pretranslator to the dial plan to reformat the information on incoming calls, you must add the VTL devices to that pretranslator. You might need to add a pretranslator to the dial plan to handle caller ID issues. See “Creating a Pretranslator for VTL Calls” on
page 70.
To add the VTL devices to the pretranslator:
1 In the NBX NetSet - Main Menu window, click Dial Plan. 2 Click the PreTranslators tab.
3 In the scroll list, select VTL. 4 Click the Devices Using button.
5 In the Devices Using Pretranslator window, scroll down in the Devices Not Using Pretranslator list until you see the devices associated with VTLs. For a 4-digit dial plan, the VTL device extensions range from 6500 through 6523. For a 3-digit dial plan, VTL device extensions range from 623 through 630.
6 Select the first VTL device extension.
7 Scroll until you can see all of the VTL device extensions.
8 Simultaneously press the Shift key and click the last VTL device extension to select the entire block of VTL device extensions.
Table 20 Virtual Tie Line Extension Ranges Platform Extension Range
V3000
4-digit dial plan
6500–6523 V3000
3-digit dial plan
The default dial plan for a NBX V3000 system is 4-digit. If you convert to a 3-digit dial plan, you must manually change each 4-digit extension to a 3-digit extension. For VTLs, you can select any unused 3-digit extension from the external extension range (600–799).
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9 To move all VTL device extensions to the Devices Using Pretranslator list, click <<.
Verification of the Virtual Tie Line
After you have configured the VTLs on each of two NBX systems, you must verify that the VTL connection works properly.
To verify that a working VTL connection exists between two systems, you must verify that:
■ Local System Verification — Verify that the configured VTLs appear on
each system.
■ Remote Access Verification — Verify that each of the systems can
access each other.
■ Placing Telephone Calls — Verify that telephone calls can be made
between all pairs of connected systems in both directions. Local System Verification
On each system you must verify that you can view the VTLs using the NBX NetSet utility. To verify that you can view the local VTLs:
1 In the NBX NetSet - Main Menu window, click Device Configuration. 2 Click the Virtual Tie Lines tab.
3 Verify that all of VTLs you have configured appear in the list.
In our example, if you perform this verification test on the Chicago NBX system, the results appear as shown in Figure 14.
Figure 14 Example: Virtual Tie Lines Tab
Remote Access Verification
To verify that each system can access the other, on each system: 1 On the Virtual Tie Lines tab, select the VTL and then click the Query
Remote button.
2 In the Query Remote System window, type the IP address of the remote system in the IP address text box. Click the Query button. If the
verification is successful, the window displays the VTLs configured at the remote site.
Example: Suppose you have installed an NBX system in Chicago, Atlanta, and Dallas, and you have configured two VTL connections on each of the Chicago and Atlanta systems. Also, the IP addresses of the three systems are:
■ Chicago — 192.168.15.100 ■ Atlanta — 192.168.25.100 ■ Dallas — 192.168.35.100
If you perform the Query Remote operation from the Chicago system to the Atlanta system, the results might look like Figure 15.
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Figure 15 Query Remote Window (Example)
The Atlanta system (IP address 192.168.25.100) shows two installed but idle VTL connections. If you performed the Query Remote test from the Atlanta office and specified the IP address of the Chicago system, it should show two installed but idle VTL connections.
If the local NBX system fails to access the remote system, an error message appears similar to the one shown in Figure 16.
Figure 16 Query Remote Error Message
If you have not yet configured the remote system to support VTLs, this message indicates that you must do so before the Query Remote operation can succeed.
If you have configured the remote system to support VTLs, the error message indicates that the local NBX system cannot access the remote system using the IP address you specified. To remedy the problem: 1 Verify that you specified the correct IP address for the remote system. 2 Verify that the remote NBX system is running properly.
3 Verify that the remote NBX system is using the dial plan which you modified to configure VTLs on that system.
4 Work with your network administrator to verify that WAN connection between the two sites is properly configured and is working.
5 Verify that the VTL extensions are included in the Devices Using Pretranslator table.
Placing Telephone Calls
The final step when verifying a virtual tie line connection is to place telephone calls in both directions between each pair of connected sites.
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