How Teams determines your Current Location and how 911 Calls are Routed

How Teams determines your Current Location and how 911 Calls are Routed

Introduction 

Configuring Microsoft Teams to comply with the RAY BAUM (Repack Airwaves Yielding Better Access for Users of Modern Services) Act  was detailed in a previous article in this series: Configuring Teams to Comply with RAY BAUMs 911 Act. 

The RAY BAUM Act is the legislation that mandates that a user’s validated current address must be provided to a Public Safety Answering Point (PSAP) when an emergency services call is made. The Act applies to emergency calls made by a company’s on premise and remote users through the firm’s telephone system. The telephone systems of many of our clients are comprised of Teams users and non-Teams endpoints such as analog phones that an emergency call could be made from. We have many customers whose telephone system are even more complex.

Emergency calls made by a Teams user are delivered to the appropriate PSAP by an Emergency Routing Service Provider (ESRP). The ERSP is build into Teams Calling Plans and Operator Connect. Teams Direct Routing customers must engage a Microsoft approved third party provider. A Direct Routing customer’s SIP Trunk provider may also offer this ERSP capability.

ERSPs will determine if a provided location is both valid and verified. Locations that are both validated and verified are routed directly to the PSAP. Calls made from all other locations are first routed to the Emergency Response Center (ERC), for Calling Plan and Operator Connect users, or the Emergency Call Routing Center (ECRC) provided by the 3rd party ERSP. In a perfect world the RAY BAUM Act and the E911 community would like to see universal automatic determination of a caller’s current location. Our current technology state particularly for remote or Work from Home (WFH) user’s is preventing us from reaching this goal.

It's important to understand when the various Teams clients will provide valid and verified addresses when an emergency call is made and whether the call will be routed directly or indirectly to the PSAP.

• All calls made from the Teams desktop, native Teams Phones (there is an exception to this noted below) and mobile clients from a corporate network will provide valid and verified addresses. These calls will be routed directly to the PSAP by Teams or the ERSP. Calls will have both a validated and verified address.
• Most calls made by remote Teams desktop users today are verified but not validated. These will be routed to the ERC or ECRC. Calls that have valid and verified locations are routed to the PSAP directly.
• Calls made by remote Teams mobile client users will have locations that are neither validated nor verified. The mobile client does not support current location verification for remote users.
• All calls made by an on premise or remote Teams user from the Teams Web Client, legacy 3rd Party IP Phones (3PIP) or Teams SIP Gateway attached devices will go to the ERC or ECRC before being routed to the PSAP.

Validated and Verified Definitions

• A valid location is an address that has been validated against the Master Street Address Guide (MSAG).
• Microsoft labels all Emergency Addresses added to Teams as being “Validated” addresses. This does not necessarily mean that the address has been validated against the MSAG.
• Addresses added through the default non-manual entry method in the Teams portal will be validated against the MSAG. Adding Emergency Addresses to Microsoft Teams can be found in the previous article in this series, Emergency Addresses and Locations in Microsoft Teams – Planning and Implementing
• If you use the manual method in the portal or add an address through PowerShell, the address will not be validated against the MSAG.
• A location is verified when:
• The location is derived from a device attached to the corporate network. The presumption is that a user’s current location will always be provided when they are using the Teams client on a device connected to the network.
• A remote Teams user verifies their current location in the Teams client.

How does the ERSP know if a location is Validated and/or Verified?

• Teams clients that support Teams Dynamic 911 or Teams Work from Home (WFH) will pass their current location information in a Presence Information Data Format Location Object (PIDF-LO) extensible markup language (XML) block to the ERSP.
• Calling Plan and Operator Connect users
• This information is passed with the call directly to the Teams Phone System “ERSP”.
• Direct Routing Users
• The information is passed to a Session Border Controller (SBC) which will forward it to the ERSP or SIP Trunk.
• The PIDF-LO and information are not passed when a Teams user is signed into a client that does not support Teams Dynamic 911 or Teams WFH.
• Included in this passed information is a field called “METHOD”. This field tells the ERSP if the location has been validated or verified:
• METHOD=LIS
• The location came from a network attached device.
• The location is both validated and verified.
• The call should go directly to the PSAP.
• METHOD=ASSIST
• The location came from a remote user.
• Teams was able to suggest a validated address to the user based on the information acquired from the device’s location services in the operating system.
• The Teams user confirmed the suggested address was in fact the user’s current address.
• The location is both validated and verified.
• The call should go directly to the PSAP.
• METHOD=CLS or MANUAL
• The location came from a remote user.
• Teams suggested a valid address to the user or was unable to suggest an address based on the information from the location service.
• The Teams user manually added or corrected the suggested address.
• The location is not validated but is verified.
• The call should go to the ERC or ECRC first.
• METHOD=NONE
• The location came from a remote user.
• One of these conditions was met:
• The call was made from the Teams Mobile client
• A valid but incorrect address was offered but the client neither confirmed nor corrected the address.
• An address was not offered, and the user did not manually add the current address.
• The location is neither validated nor verified.
• There will probably be no location information in the PIDF-LO at all.
• The call should go to the ERC or ECRC first.

ERSP handling of the METHOD Field

• We now know that the ERSP will route the emergency call to the PSAP or the ERC\ECRC based on the value found in the METHOD field of the PIDF-LO.
• LIS and ASSIST will go to the PSAP, all others to the ERC\ECRC.
• Most ERSPs have an additional layer to their routing logic.
• ERSPs generally require the customer to create and maintain a database of their numbers with the ERSP. Many use this for billing purposes.
• The ERSPs typically require that a location be associated with each number added to the database. These are static location assignments to numbers.
• The ERSPs can use this location when an emergency call is made from devices that don’t pass the location in the PIDF-LO.
• Calls made from these devices are usually routed directly to the PSAP with the database record’s location for the number:
• Teams Web Client
• 3PIP Phones
• Teams SIP Gateway attached devices
• Non-Teams analog devices that emergency calls could be made from
• When the ERSP receives an emergency call they will first check to see if the calling number is in the database. If it is not, regardless of the location being validated or verified, the call will be routed to the ECRC before routing to the PSAP.

Teams Client Dynamic 911 and Work from Home Location Processing

• Support for Teams Dynamic 911 and WFH is currently inconsistent in the Teams clients.
• Teams Dynamic 911 is supported by:
• Windows Desktop Client
• Mac Desktop Client
• Native Teams Phones
• These are not currently supported in GCC High Office 365 Tenants
• IOS\Android Mobile Clients
• Teams WFH is supported by:
• Windows Desktop Client
• Mac Desktop Client
• IOS\Android Mobile Clients
• These clients can request a location from the operating system and will send it to Teams to try to get a suggested address.
• Regardless of the result, the address cannot be confirmed or edited.
• Neither Teams Dynamic 911 nor WFH are supported by these clients:
• Teams Web Client
• Legacy 3PIP Phones
• Teams SIP Gateway attached devices

Legend

• Diagrams on the following pages are presented that show how:
• The current location of an emergency caller is determined.
• The value of the “METHOD” field that is passed to the ERSP.
• The color of the lines shows the location determination flow for clients that support Teams Dynamic 911 and Teams WFH:

• At the bottom of each diagram, are rectangles showing what the user will see for a location in their Teams client and whether they can edit or reset the location.
• The boxes have a black, blue, red, or red\blue border designating the validation and verification status of the location.

Teams Windows and Mac Desktop Clients 

Native Teams Phones 

Teams IOS\Android Mobile Clients

Web Client, 3PIP Phones and Teams SIP Gateway Devices

Summary 

• The goal for E911 is for emergency calls to go directly to the PSAP. 
• The current state of technology is making this difficult to attain for remote Teams users. Most emergency calls from a remote Teams user will be routed to the ERC\ECRC by the ERSP. 
• As the technology evolves, more calls will be routed directly to the PSAP. 
• There is inconsistent support for Teams Dynamic 911 and Teams WFH in the Teams clients. 
• Validation and verification of a Teams user’s current location are the determinates of whether a call goes directly to the PSAP or indirectly through the ERC\ECRC. 

Work with our team of Cloud Computing Consultants who have done this so many times they know all of the “minefields” to prevent missteps.