Configuring SBC Edge and Lync to Support Enhanced Emergency (911) Services

In this article, we describe the necessary steps to configure SBC Edge and Lync for Enhanced Emergency Services (E911) support.

Topology

Overview

There are two types of 911 (emergency) calls, Basic and Enhanced:

• Basic 911 calls contain no location information
• Enhanced 911 calls do contain location information

When Enhanced Emergency Services are enabled in Lync, location information about a 911 caller is passed to the destination (emergency services dispatcher, police, fire, etc.). 911 calls from Lync clients signed-in at an office location include location information, calls from Lync clients not signed in at an office location are connected to the destination using a fallback 911 route which does not contain location information.

Related Articles

• Configure Enhanced 9-1-1
• Using Lync Setup for E911 Configuration (uses a configuration wizard)

Central Site Configuration

The Lync side configuration steps are accomplished using the following tools:

• Lync Server 2010 Configuration Manager
• Lync Server Management Shell

Location Policy Configuration

To configure the location policy:

1. Launch Lync Server 2010 Configuration Manager.
   
   
2. Click Network Configuration on left pane.
   
   
3. Click Location Policy on right pane.
   
   

4. Edit the Global Location Policy as shown below.

   Configure Location Policy

   

Dial Plan Configuration

To configure a dial plan:

1. Launch Lync Server 2010 Configuration Manager.
   
   
2. Click Voice Routing on left pane.
   
   
3. Click Dial Plan on right pane.
   
   
4. Edit the Dial Plan as required.
   
   

5. Add a new Normalization Rule for 911 call as shown below.

   Configure Dial Plan

   

Route Configuration

1. Launch Lync Server 2010 Configuration Manager.
        
2. Click Voice Routing on left pane.
   
   
3. Click Route on right pane.
   
   
4. Edit the relevant Voice Route and add a new Pattern for 911 call.
        

5. Be sure to have the relevant SBC Edge gateway selected in Associated Gateways field as shown below.

   Route Configuration

   

Trunk Configuration

1. Launch Lync Server Management Shell.
   
   
2. Check the Trunk Configuration using Get-CSTrunkConfiguration command.
   
   
3. Verify that EnablePIDFLOSupport attribute is True. If not:
   1. Run the Set-CSTrunkConfiguration -EnablePIDFLOSupport $True script.
   2. Press Enter.
   3. Verify that script Get-CSTrunkConfiguration returns a EnablePIDFLOSupport attribute as True, as shown below.

Trunk Configuration

Create a Location Information Server (LIS) Subnet

This set of steps creates a Location Information Server (LIS) subnet. LIS Subnets are used to associate a location with a specific subnet. LIS Subnets are used in Enhanced 9-1-1 (E9-1-1) Enterprise Voice implementations to notify an emergency services operator of the caller's location.

To create a Location Information Server Subnet:

1. Launch Lync Server Management Shell.
   
   
2. Type Set-CsLisSubnet -Subnet 134.56.105.0 -Description "Cubicle" -Location "Office" -CompanyName "Ribbon" -HouseNumber "6900" -PreDirectional N -StreetName "Paseo Padre" -StreetSuffix "Pkwy" -City "Fremont" -State "CA" -PostalCode 94555 -Country US as shown below.
   
   
3. Press Enter.

Create LIS Subnet

Location Policy Configuration

1. Launch Lync Server 2010 Configuration Manager.
   
   
2. Click Network Configuration on left pane.
   
   
3. Click Location Policy on right pane.
   
   
4. Edit the relevant Voice Route.
   
   
5. Select the Enable enhanced emergency services check box.

Location Policy Configuration

Ribbon SBC Edge Configuration

The configuration steps on the SBC Edge are achieved directly via the WebUI broken down in the following sections:

• SIP Profiles
• Number Transformation
• Call Routing

SIP Profiles

1. In the WebUI, click the Settings tab.
   
   
2. In the left navigation pane, go to SIP > SIP Profiles > relevant SIP Profile.
   
   
3. In the MIME Payloads panel:
   1. Configure the ELIN Identifier field as LOC.

   2. Configure the PDIF-LO Passthrough field as Enable.

Number Transformation

This example uses two Transformation Tables to route calls to a 911 Provider over SIP trunking:

• Transformation for calls from Lync clients signed-in at Office Locations.
• Transformation for calls from Lync clients signed-in at Remote Locations such as Starbucks, etc..

Transformation Table for calls to E911

A Transformation entry is created for Lync E911, which includes table entries for Called Address/Number, ELIN Identifier, and Callback Pool Identifier (the emergency call back number table or Pasthrough ELIN number used for calls destined to 911). For specific information about the Passthrough ELIN Number, see Creating and Modifying Entries to Transformation Tables.

For easy identification, the Description field matches the Scenario description you configured in Lync Setup.

1. In the WebUI, click the Settings tab.
2. In the left navigation pane, click Transformation.
3. Click  to create a new Transformation Table. Configure the new table with the following ELIN Identifier, Called Address/Number, and Calling Address/Number field types: 

Transformation Table for 911 Fallback calls

1. In the WebUI, click the Settings tab.
2. In the left navigation pane, click Transformation.

3. Click  to create a new Transformation Table. Configure the new table with the following ELIN Identifier, Called Address/Number, and Calling Address/Number field types:

   Transformation Table Entries - 911 Fallback

   Input Field Type	Input Field Value	Output Field Type	Output Field Value	Match Type
   ELIN Identifier	(.*)	Calling Name	OtherLocations	Mandatory (Must Match)
   Called Address/Number	\+911	Called Address/Number	9911	Mandatory (Must Match)
   Calling Address Number	\+.#(\d{4})	Calling Address/Number	+1510246\1	Mandatory (Must Match)

   Use the appropriate value for your location in the Calling Address/Number > Output Field Value field.

Call Routing

A Lync E911 entry is created in the Call Routing Table for routing calls from SIP to ISDN. For more information about Call Routing Tables, see Managing Call Routing Tables.

1. In the WebUI, click the Settings tab.
2. In the left navigation pane, go to Call Routing Table.
3. Click the relevant Call Route table used for calls received from Lync.
   
   

Add two entries (see below for configuration):  one for calls with configured Office Location Information, and another one that does not have the Location Information as Office. Note that both route entries are destined to 911 Provider over a SIP Trunk.

Call Flow

In the example configuration, when a 911 call from Lync client arrives on the SBC Edge with the Location Information as Office, Lync will then provide the relevant location profile in the Inbound INVITE message. Ribbon SBC 1000/2000 then passes this information to the 911 Provider in the outbound INVITE message.

This can be verified in the logs by tracing the relevant inbound INVITE message from Lync to the SBC Edge:

Tracing Relevant Inbound INVITE Message