Best Practice - Configuring SBC Edge for Microsoft Teams Direct Routing

Overview

This Best Practice details the configuration required for interoperability between Ribbon SBC Edge (SBC 1000/2000 and SBC SWe Lite) and Microsoft Teams Direct Routing.

How SBC Edge Interoperates with Microsoft Teams Direct Routing

Microsoft Teams Direct Routing interface enables the Ribbon SBC Edge to connect to the Microsoft Teams. The SBC Edge can be connected to almost any telephony trunk or interconnect a 3^rd party non-Teams client. The scenario enables the following:

• Virtually any PSTN trunk can be used with Microsoft Teams Direct Routing
• Interoperability between customer-owned telephony equipment (such as 3^rd party PBXs and analog devices) and Microsoft Teams Direct Routing 

Microsoft supports only validated devices (such as the Ribbon SBC Core and Edge) to connect to the Direct Routing interface.

Topology Example

The example below shows the connection topology, which includes the following: 

• Third-party party PBX, Analog devices and the Administrator's management station, located on the LAN
• Microsoft Teams Direct Routing on the WAN
• SIP trunk from a third-party provider on the WAN

The topology example below uses an SBC 1000/2000.

SBC 1000-2000 and Microsoft Teams Direct Connect Interface - Topology Example

Prerequisites

Microsoft Teams Direct Routing 

Consult the Microsoft documentation for the Direct Routing interface configuration guidelines, including the RFC standards and the syntax of SIP messages.

Ribbon SBC Edge

Obtain IP Address/FQDN/Public Certificate

Before you begin, ensure that you have the following for every SBC to be paired:

• Public IP address

  • If you plan to use Media Bypass, Microsoft requires ICE Lite. ICE RFC 5245 requires a public IP address assigned on the SBC interface without NAT.

  • If you do not plan to use Media Bypass, ICE Lite is not required. The SBC can use a Public IP behind a NAT.

• FQDN name matching the Public IP address.
  
• Public certificate (issued by one of the supported CAs; see Domain Name for details about Certification Authorities). Wild Card certificates are supported.
  

Obtain Domain Name

The SBC FQDN must be from one of the Domain names registered in “Domains” of the Tenant. The table below lists Domain Name examples.

Domain Name Examples

Domain Name	Use for SBC FQDN?	FQDN Names - Examples
SonusMS01.com		Valid names: aepsite6.SonusMS01.com
hybridvoice.org		Valid names: sbc1. hybridvoice.org ussbcs15. hybridvoice.org europe. hybridvoice.org Non-Valid name: sbc1.europe.hybridvoice.org (requires registering domain name europe. hybridvoice.org in “Domains” first)

Configure Domain Names - Example

 

Download Latest Software Version

Ensure you are running the latest SBC Edge Release:

*Teams Direct Routing With/Without Media Bypass - Example Below

Teams Direct Routing - Without Media Bypass

 

Configuring SBC Edge

This section provides details on how to configure Ribbon SBC Edge for interoperating with Microsoft Teams Direct Routing.  

Configure a Certificate for the SBC Direct Routing Interface 

Microsoft Teams Direct Routing only allows TLS connections from the SBC for SIP traffic with a certificate signed by one of the trusted certification authorities.

Request a certificate for the SBC External interface and configure it based on the example using GlobalSign as follows:

• Generate a Certificate Signing Request (CSR) and obtain the certificate from a supported Certification Authority.
• Import the Public CA Root/Intermediate Certificate on the SBC.
• Import the Microsoft CA Certificate on the SBC.
• Import the SBC Certificate.

Step 1: Generate a Certificate Signing Request and obtain the certificate from a supported Certification Authority (CA)

1. Access the WebUI.
2. Access Settings > Security > SBC Certificates.

3. Click Generate Sonus CSR.

   Many CA's do not support a private key with a length of 1024 bits. Validate with your CA requirements and select the appropriate length of the key.

4. Enter data in the required fields.

5. Click OK. After the Certificate Signing request finishes generating, copy the result to the clipboard.

   Generate Certificate Signing Request

   

6. Use the generated CSR text from the clipboard to obtain the certificate.
    

Step 2: Deploy the SBC and Root/Intermediate Certificates on the SBC

After receiving the certificates from the certification authority, install the SBC Certificate and Root/Intermediate Certificates as follows:

1. Obtain Trusted Root and Intermediary signing certificates from your certification authority.
2. Access the WebUI.
3. To install Trusted Root Certificates, click Settings > Security > SBC Certificates > Trusted CA Certificates.
   
4. Click Import and select the trusted root certificates.
5. To install the SBC certificate, open Settings > Security > SBC Certificates > Sonus Certificate.

6. Validate the certificate is installed correctly.

   Validate Certificate

   

7. Click Import  and select X.509 Signed Certificate.

8. Validate the certificate is installed correctly.

   Validate Certificate

   

Step 3: Deploy Baltimore Trusted Root Certificate

The Direct Routing interface has the DNS name sip.pstnhub.microsoft.com. On that interface, the certificate is signed by Baltimore CyberTrust Root with Serial Number: 02 00 00 b9 and SHA fingerprint: ‎d4:de:20:d0:5e:66:fc: 53:fe:1a:50:88:2c:78:db:28:52:ca:e4:74.

To trust this certificate, your SBC MUST have the certificate in Trusted Certificates storage.

1. Download the certificate from https://cacert.omniroot.com/bc2025.crt and use the steps above to import the certificate to the Trusted Root storage. 

   Deploy Certificate

   

Configure TLS Profile

The TLS profile defines the crypto parameters for the SIP protocol.

Create a TLS profile as follows:

1. In the WebUI, click the Settings tab.

2. In the left navigation pane, go to Security > TLS Profiles.

3. Click the CreateTLS Profile ( ) icon at the top of the TLS Profile page.

4. Configure the parameters shown below. Leave all other parameters as default.

   TLS Configuration - Example Values

   Parameter	Example Value
   Description	Microsoft Phone system (example name)
   TLS Protocol	TLS 1.2 Only
   Validate Client FQDN	Disabled

   TLS - Example

   

Configure Node-Level Settings

1. In the WebUI, click the Settings tab.

2. In the left navigation page, access System > Node-Level Settings.

3. Configure the NTP and DNS Server with the appropriate configuration.

   Node-level Settings - Example

   

Configure Node Interface

1. In the WebUI, click the Settings tab.

2. In the left navigation pane, go to Node Interfaces > Logical Interfaces.

3. Configure the parameters shown below:

   The Media Next Hop IP field (available on SWe Lite only; not shown below) must be configured with the Default Gateway for this interface.

   Logical Interfaces Configuration - Example Values

   Parameter	Example Value
   Description	To Microsoft Phone System
   Admin Interface	Enable
   IP Assign Method	Static (example)
   Primary Address	<Public IP of your SBC> in the example 192.168.211.80
   Primary Netmask	<Mask of Public Interface of  your SBC> in the example 255.255.255.0

   Logical Interfaces - Example

   

Configure SIP Profile

The SIP Profile enables configuration for parameters, such as SIP Header customization, option tags, etc.

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access SIP > SIP Profiles.

3. Click the ( ) icon at the top of left corner and add a new SIP profile.

4. Configure parameters shown below:

   SIP Profile Configuration - Example Values

   Parameter	Example Value
   Description	Microsoft Phone System
   FQDN in From Header	Sonus SBC FQDN
   FQDN In Contact Header	Sonus SBC FQDN
   Origin Field Username	<FQDN of SBC>

   SIP Profile - Example

   

Configure Media Crypto Profile

The Media Crypto Profile defines the encryption mechanism to use between the SBC and the Microsoft Direct Routing Interface.

Add a Media Crypto Profile:

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access Media > Media Crypto Profiles.
3. Click the ( ) icon at the top of  left corner and add a new Media Crypto Profile.

4. Configure the parameters as shown below. Leave all other parameters as default.

   Media Crypto Profile Configuration - Example Values

   Parameter	Example Value
   Description	Microsoft Phone System
   Operation Option	Required
   Crypto Suite	AES_CM_128_HMAC_SHA1_80

   Media Crypto Profile - Example

   

Configure Media List

The Media List defines the codecs and if the crypto mechanism will be used.

Create a media Profile:

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access Media >Media List.
3. Click the ( ) icon at the top of  left corner and add a new Media List.

4. Configure the parameters as shown below. Leave all other parameters as default.

   Media List Configuration - Example Values

   Parameter	Example Value
   Description	Microsoft Phone System
   Media Profiles List	Default G711a Default G711u NOTE: See Microsoft documentation for the list of codecs supported by Microsoft.
   Crypto Profile ID	Microsoft Phone System (created on the previous step)

   Media List - Example

   

Configure SIP Server Tables

SIP server tables defines the information for the SIP interfaces connected to the Ribbon SBC; it must be configured to support the Microsoft Phone System.

Add a new SIP Server Table:

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access SIP > SIP Server Tables
   

3. Click the ( ) icon at the top of  left corner and add a new SIP Server Table.

   Create SIP Server Table

   

4. Configure the parameters as shown below. Leave all other parameters as default.

   SIP Server Table Configuration - Example Values

   Parameter	Example Value
   Row ID	Assigned by the system
   Description	Microsoft Phone System

Configure Parameters of new SIP Server Table

Configure the parameters of the SIP Server table:

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access SIP > SIP Server Tables.
3. Select the name of the table created in the previous step.
4. At the top left corner of the main configuration pane click Create New SIP Server, select IP/FQDN and add the pairing to the Direct Routing interface .

5. Repeat the operation for the other two SIP Server entries. Leave all other parameters as default.

   SIP Server 1 Table - Example Values

   Parameter	Value
   Priority	1
   Host	sip.pstnhub.microsoft.com
   Port	5061
   Protocol	TLS
   TLS Profile	Microsoft Phone System
   Monitor	SIP Options

   SIP Server 2 Table - Example Values

   Parameter	Value
   Priority	2
   Host	sip2.pstnhub.microsoft.com
   Port	5061
   Protocol	TLS
   TLS Profile	Microsoft Phone System
   Monitor	SIP Options

   SIP Server 3 Table - Example Values

   Parameter	Value
   Priority	3
   Host	sip3.pstnhub.microsoft.com
   Port	5061
   Protocol	TLS
   TLS Profile	Microsoft Phone System
   Monitor	SIP Options

   SIP Server - Example

   

Configure Voice routing

Configure Routing Logic per Ribbon Documentation. Refer to Working with Telephony Routing.

Configure Voice Routing

Configure Transformation Table

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access SIP > Transformation Tables.
   

3. Click the ( ) icon at the top left corner to add a new Transformation Table.

   Create Transformation Table

   
    

4. Configure the parameters as shown below.

   Transformation Table - Example Values

   Parameter	Value
   Row ID	Assigned by the system
   Description	Microsoft Phone System (example name)

Configure Call Routing Table

To add and configure a new Call Routing Table:

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access Call Routing Table.
   

3. Click the () icon at the top of  left corner and add a new Call Routing Table.

   Create Call Routing Table

    

4. Configure the parameters as shown below. Click OK.

   Call Routing Table - Example Values

   Parameter	Value
   Row ID	Assigned by the system
   Description	Microsoft Phone System (example name)

5. From the left navigation pane, click on the Call Routing > Microsoft Phone System (the entry created in the last step).

6. Click the ().

7. Configure the parameters as shown below. Leave all other parameters as default.

8. Click OK.

   Call Routing Table Configuration - Example

   Parameter	Value
   Description	From Microsoft Phone System (example name)
   Number/Name Transformation Table	Microsoft Phone System
   Destination Signaling Groups	Choose the Signaling Group of a local equipment

   Call Routing Table - Example

   

Configure Signaling Group

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access Signaling Groups
   

3. For the SBC 1000-2000, from the Create Signaling Group drop down box, select SIP Signaling Group.

4. For the SWe Lite, click Add SIP SG.
   

5. Configure the parameters as shown below. Leave the default values for all other parameters.

6. Click OK.

   Signaling Group Configuration - Example Values

   Parameter	Value
   Description	Microsoft Phone System
   SIP Profile	Microsoft Phone System (from the previous steps)
   Media List ID	Microsoft Phone System (from the previous steps)
   Signaling Media/Source IP	Ethernet 1 (example, pick the interface which faces the Microsoft Phone System)
   Listen Port	5068 (arbitrary port) TLS TLS Profile ID: Microsoft Phone System (from the previous steps)
   Federated IP/FQDN	sip-all.pstnhub.microsoft.com
   SIP server table	Microsoft Phone System (from the previous steps)
   Load Balancing	Priority
   SIP Profile	Microsoft Phone System (from the previous steps)
   Call Routing Table	Microsoft Phone System (from the previous steps)
   Outbound NAT traversal[1]	Static NAT
   NAT Public IP	192.168.211.80 (Only required if “Static NAT” is selected)

   
   

   ---

   [1] Please ignore if the SBC has a Public IP assigned on the interface. The NAT Public IP is required only when the SBC is behind a NAT.

   Signaling Group - Example

   

Configure REFER and Re-Invites for Call Forwarding

When the remote peer forwards all the REFER messages without checking the destination, the SBC EDGE can be reconfigured to force the call through the remote peer. See below for configuration.

Modify Message Manipulation

1. In the WebUI, click the Settings tab.

2. In the left navigation pane, go to SIP > Message Manipulation > Message Rule Table.

3. Create a new Message Rule Table configured as shown below.

   Create Message Rule Table

   

4. In the left navigation pane, click the newly created Rule Table entry. 

5. Click Create Rule > Request Line Rule.

6. Configure the Request Line Rule as shown below.

Modify Signaling Group

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access Signaling Groups
   

3. Access the Signaling Group used for Teams.
   

4. Assign the Message Rule Table to the Teams Signaling Group as Inbound Message Manipulation.

   Configure Signaling Group

   

Modify Transformation Table

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access SIP > Transformation Tables.

3. Click the ( ) icon at the top left corner to add a new Transformation Table.

4. Configure as shown below.

   Create Transformation Table

   

Modify Call Routing

1. In the WebUI, click the Settings tab.
2. In the left navigation page, access Call Routing Table.
   

3. In the Routing Table designated "From Teams," create a routing entry that points to the destination Teams Signaling Group (this must be the first routing entry in the list) and assign the newly created Transformation Table.

   Create Call Routing Entry

   

Confirm the Configuration

Validate SIP Option

1. In the WebUI, click the Settings tab.
2. In the left navigation pane, access Signaling Groups.
3. For the signaling group configured for Microsoft Teams Direct Routing, click Counters.
4. Confirm the number of Incoming and Outgoing SIP Options.
5. Confirm the number of Incoming and Outgoing 2xx responses.

Incoming and Outgoing Counters

Place a Test Call

Place a test call as follows:

1. In the WebUI, click the Diagnostics tab.
2. In the left navigation pane, click Test a Call.
3. Configure the parameters as shown below.

4. Click OK.

   Place a Test Call - Parameters

   Parameter	Value
   Destination Number	Number assigned to a Teams user.
   Origination/Calling Number	Number assigned to a Local user
   Call Routing Table	The routing table that handles the call from Local resource.

   Place a Test Call - Configuration

   

   Place Test Call - Example

   

Known Issues

Outbound call from Teams to PSTN show as Anonymous when ForwardPAI is enabled on the CSOnlinePSTNGateway

When forward PAI is enabled on the Tenant CsOnlinePSTNGateway, Microsoft adds a PAI and Privacy SIP header on the outbound call to the SBC. RFC 3325 defined the 'id' value for the Privacy header, which is used to request the network remove the P-Asserted-Identity header field.

Different behavior may be required, as follows:

1. If the SBC is in a trusted network, it should not remove the PAI information and allow the last equipment to remove it. SBC will forward the FROM, PAI and Privacy header.
   • Outbound SIP profile -> Send Assert Header: Trusted Only (Default)
   • Outbound SIP profile -> Trusted Interface: Enable (Default)
2. If the SBC is the last trusted equipment, it should hide the PAI information. SBC will remove the PAI and Privacy header and make the FROM header Anonymous.
   • Outbound SIP profile -> Send Assert Header: Trusted Only (Default)
   • Outbound SIP profile -> Trusted Interface: Disable
3. If the SBC is in a trusted network but the equipment behind it makes the call anonymous due to the Privacy header (and the customer does not want the call anonymous), the SBC can remove the PAI and Privacy header and keep the FROM Header.
   
   • Outbound SIP profile -> Send Assert Header: Never
   • Outbound SIP profile -> Trusted Interface: Enable (Default)

Teams Direct Routing Refer Scenario

The SBC Edge supports REFER and Re-Invites for call forwarding. To handle a scenario for when the remote peer forwards all the REFER messages without checking the destination, the SBC EDGE can be reconfigured to force the call through the remote peer.

For configuration, see Configure Forward Handling.