# Configuring a Virtual Loopback IP Trunk

## Description

Configuring a Virtual Loopback IP Trunk overcomes a limitation that restricts the number of Analog Gateways that MiVoice Business can host to five. The limit is imposed by ARS, which supports a maximum of six routes per route list. The route lists are used to ensure that outgoing external calls (especially E911 calls) for hosted phones are routed through IP Trunking to the appropriate gateway.

## Conditions

- All IP trunks have been successfully established between the host MiVoice Business system and all remote Analog Gateways.

- All IP phones on the gateways are registered at the host MiVoice Business system.

## Programming

The following example is the programming required at the Head Office system in Los Angeles. The branch offices serviced by the Analog Gateways are located in Chicago and New York. Although there are only two gateways in the example, the solution described can be extended to any number of gateways.

The Head Office is connected to the gateways over an IP trunk belonging to trunk group 10. Trunk Group 10 is in Route Number 20.

Programming the Head Office MiVoice Business system:

1. Create a virtual loopback IP trunk.

- In the IP/XNET Trunk Groups form ( ), create a new XNET Trunk group (the example uses trunk group 10) and enter system number of the Head Office MiVoice Business system in the PBX Number field. Enter values for Local Profile Number and Maximum Network Hops. Use values you would for regular IP trunks.

- In the ARS Routes form ( ), select a new Route Number (20 in the example) and enter 10 in the XNET Trunk Group Number and Digit Modification Number fields.

2. Program the virtual loopback trunk to insert a default account code.

3. In ARS Digit Modification Plans form ( ), select the Digit Modification Number 10, and enter <D> in the Digits to be Inserted field.

4. Enter the required value for Number of Digits to Absorb. The value to use depends on how traffic is normally routed. Typically, 0 is expected.

3. In the ARS Leading Digits form ( ), define a range of ARS leading digits to use to route 911 calls.

For the purposes of the example, the digits programmed are as follows:

3. ARS leading digit 81 followed by 911 to route calls to the Chicago gateway

4. ARS leading digit 82 followed by 911 to route call to the New York gateway.

   TIP: If the Analog Gateways are clustered, consider using CESID
   Customer Emergency Service Identification. The CESID is a number that uniquely identifies the device that dialed 911. The CESID is fed into the automatic location identification (ALI) database at the Public Safety Answering Point (PSAP) so that emergency services can be dispatched to the correct location. digits as the ARS leading digits followed by 911 to route calls to the appropriate gateway.

4. Map the specific ARS leading digit from Step 3 to the corresponding account code index in Default Account Codes form ( )— for example,

5. enter 81 next to account code index 1 for Chicago extension;

6. enter 82 next to account code index 2 for New York extensions

5. Associate extensions at the gateways with the appropriate account code index in the Station Attributes form ( )— for example,

6. enter 1 in the Default Acct. Code field for Chicago extensions,

7. enter 2 in the Default Acct. Code field for New York extensions.

6. Create a route list to differentiate the local (Head Office) users from the gateway users based on Class of Restriction (COR)
   A class of restriction controls station and trunk access to trunk circuits. It performs functions similar to toll control and is programmable on a station (or trunk) basis using the Class of Restriction Groups and ARS Routes forms..

7. In the ARS Route Lists form ( ), select a route list number (for example, 11) and assign the first and second choice route. The first choice should be a local 911 route for local users and the second choice should be for all remote users at the Analog Gateways (Route 20 in the example).

   NOTE: Local users must be COR restricted to access the first choice only, while remote users must be restricted to the second choice only.

7. In the ARS Digits Dialed form ( ), set up routing for 911 calls dialed at each location.

The programming for the example would be as follows:

a) 911 or 9911 depending on the local dialing scheme. Select Route List 11 as the Termination Type and Number.

b) 81911 or 819911 and select the existing IP trunk route to Chicago as the Termination Type and Number

c) 82911 or 829911 and select the existing IP trunk route to New York as the Termination Type and Number

TIP: In the "Number of Digits to Follow" field for Step 7b and Step 7c, specify how many of the digits inserted by the default account code programmed in Step 4 should be absorbed.

8. Program similar 911 routing at the Chicago and New York gateways.

NOTE: The maximum number of VoIP Calls specified in the ICP/PBX Networking form ( ) must take traffic (911 and regular calls) over the loopback IP trunk take into account.