Configuring Location-Based Emergency Routing

The device identifies the geographical location of emergency callers by their ELIN numbers, which is present in the PIDF-LO XML body of received SIP INVITE messages. Therefore, you need to configure the device to route emergency calls to a destination (i.e., emergency center such as the police) that is appropriate to the caller's ELIN number. As the destination of incoming calls is the emergency number (e.g., 999), the device needs to manipulate the destination number to a number that represents the caller's local emergency center (e.g., +4420999 for London police).

To add manipulation rules for location-based emergency routing, you need to use the Destination Phone Number Manipulation for IP-to-Tel Calls table. In this table, you need to use the ELIN number (e.g., 5000) as the source prefix, with the "ELIN" string value added in front of it (e.g., ELIN5000) which is used by the device to identify the number as an ELIN number (and not used for any other routing processes etc.). For each corresponding ELIN source number prefix entry, you need to configure the manipulation action required on the destination number so that the call is routed to the appropriate destination.

Following is an example of how to configure location-based emergency routing:

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Assumptions:

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Company with offices in different cities -- London and Manchester.

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Each city has its local police department.

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In an emergency, users need to dial 999.

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Company employs Microsoft Skype for Business for communication between employers, and between employers and the external telephone network (PSTN). In other words, all employers are seemingly (virtual) in the same location in respect to the IP network.

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ELIN numbers are used to identify the geographical location of emergency calls dialed by users:

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London ELIN is 5000.

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Manchester ELIN is 3000.

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Configuration Objectives:

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Emergency calls received from London office users are routed by the device to the London police department (+4420999).

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Emergency calls received from Manchester office users are routed by the device to the Manchester police department (+44161999).

The international code, +44 for England is used for IP routing considerations, but can be omitted depending on your specific deployment.

The above scenario is configured as follows:

1.

Enable location-based emergency routing, by loading an ini file to the device with the following parameter setting:

a.

Open the Gateway Advanced Settings page (Setup menu > Signaling & Media tab > Gateway folder > Gateway Advanced Settings).

b.

From the 'E911 Gateway' drop-down list [E911Gateway], select Location Based Manipulations.

2.

In the Destination Phone Number Manipulation for IP-to-Tel Calls table (see Configuring Source/Destination Number Manipulation), add the following two rules for manipulating the destination number of incoming emergency calls, based on ELIN numbers:

Index 0 manipulates the destination number for London emergency callers; Index 1 manipulates the destination number for Manchester emergency callers.