SIP Trunk Setup for Microsoft Teams Phone

Use Voyced as an external SIP provider

This guide explains how to connect your Voyced telephone number and SIP service to Microsoft Teams Phone.

Microsoft Teams Phone allows users to make and receive business telephone calls from the Teams desktop application, mobile application and compatible Teams telephones.

Unlike a conventional telephone system, Microsoft Teams cannot register directly with an external SIP provider using a SIP username and password.

To use Voyced, you need Microsoft Teams Direct Routing and a supported Session Border Controller (SBC).

The SBC connects the two services and handles the differences in SIP signalling, registration, security and telephone number formatting.

This guide covers:

• Microsoft Teams Phone

• Microsoft Teams Direct Routing

• Connecting a certified SBC to Microsoft Teams

• Configuring Voyced SIP registration on the SBC

• Incoming and outgoing telephone calls

• Telephone number assignment

• Caller ID and number formatting

• Testing and troubleshooting

What You'll Need

Before you begin, make sure you have:

• Administrator access to your Microsoft 365 organisation

• Access to the Microsoft Teams admin center

• A Microsoft Teams Phone licence for each user who needs telephone calling

• A Microsoft-certified Session Border Controller

• An SBC that supports SIP registration towards an external provider

• A public domain name for your SBC

• A trusted TLS certificate for that domain

• Suitable network and firewall access

• An active Voyced telephone number

Your Voyced SIP details:

Replace the username and password placeholders with your actual Voyced service details.

Requirements Before You Begin

Understand How the Connection Works

Microsoft Teams and Voyced use different connection methods.

The SBC provides the connection between them.

Microsoft Teams Phone
        |
        | Direct Routing
        | SIP over TLS
        | Secure audio (SRTP)
        |
        v
Microsoft-Certified SBC
        |
        | SIP Registration
        | Username and Password
        | UDP Port 5060
        | Standard RTP Audio
        |
        v
    sip.voyced.eu
        |
        v
External Telephone Network

The SBC must handle both sides of this connection.

Connection Requirements

Microsoft Teams uses secure SIP signalling and media through Direct Routing.

The SBC must convert signalling and media as needed for the Voyced connection.

Supported SBCs

Microsoft maintains a list of certified SBC products.

Examples include:

• AudioCodes Mediant SBC

• AudioCodes Virtual Edition SBC

• Ribbon SBC 1000 / 2000

• Ribbon SBC SWe Edge

Check that your selected product and firmware version are certified for Microsoft Teams Direct Routing.

Also confirm that the SBC supports SIP registration using credentials on its external carrier connection.

Microsoft certification alone does not guarantee that every SBC model supports every external registration arrangement.

You can use an SBC installed on your premises, a virtual SBC or a managed Direct Routing SBC service.

The SBC must be configured for your Microsoft 365 organisation and your Voyced account.

Microsoft Licensing

Users making or receiving external telephone calls need Microsoft Teams Phone licensing.

They do not need a Microsoft Calling Plan simply because they use Teams Phone.

Direct Routing allows a separate telephone provider, such as Voyced, to handle external calls.

Licensing depends on your Microsoft 365 subscription and any features you enable.

SIP Trunk Setup Steps

1. Check Your Microsoft Teams Phone Licences

Open the Microsoft 365 admin center.

Navigate to:

Billing → Licences

Check that the users who need external calling have the required Microsoft Teams Phone licences.

For each user:

1. Open Users → Active users.

2. Select the user.

3. Review the assigned licences.

4. Confirm Microsoft Teams Phone is included.

5. Save any changes.

Your users should also be configured for Teams calling.

Microsoft requires Direct Routing users to be homed online and use a supported Teams coexistence mode.

For a normal cloud-based Teams deployment, use Teams Only mode.

2. Prepare Your SBC Domain Name

Your SBC needs its own public hostname.

For example:

sbc.yourcompany.com

This is an example. Use a hostname belonging to your organisation.

The SBC hostname must belong to a verified domain in your Microsoft 365 organisation.

You cannot use an onmicrosoft.com hostname as the SBC domain.

Create a DNS record pointing your SBC hostname to its public IP address.

Example:

If you use a separate subdomain, verify that subdomain in Microsoft 365 when required.

Check that the hostname resolves to the correct public address.

3. Install the SBC TLS Certificate

Microsoft Teams Direct Routing requires a trusted TLS certificate on the SBC.

The certificate must:

• Match the SBC hostname

• Be issued by a trusted public certificate authority

• Support server authentication

• Be valid and not expired

• Include the required certificate chain

For example:

sbc.yourcompany.com

The certificate must match that hostname.

Install the certificate using your SBC's administration interface.

Microsoft recommends generating the certificate request directly from the SBC where supported.

The correct certificate installation procedure depends on the SBC manufacturer.

After installation, confirm that the SBC can present its certificate during a TLS connection.

4. Configure the Microsoft Teams Side of the SBC

Open your SBC administration interface.

Create a SIP connection for Microsoft Teams Direct Routing.

The relevant Microsoft SIP proxy addresses are:

For normal commercial Microsoft 365 environments, these are the standard Direct Routing endpoints.

Configure:

Use the configuration procedure supplied by your SBC manufacturer.

Microsoft Teams must recognise the SBC through its trusted hostname and certificate.

This connection does not use your Voyced SIP username or password.

5. Configure the Voyced Side of the SBC

Create another SIP connection on your SBC.

Name it:

Voyced

Enter:

The SIP server must be:

sip.voyced.eu

Use the server hostname rather than a fixed IP address.

The username and authentication username should contain your Voyced SIP account number.

Example:

442012345678

Enter your Voyced service password.

If your SBC offers separate authentication settings for REGISTER and INVITE requests, configure the Voyced credentials for the required registration and outbound authentication.

Save the provider connection.

6. Configure SIP Registration

Open the Voyced connection's registration settings.

Use:

A normal SIP registration may include the following messages:

REGISTER
401 Unauthorized
REGISTER with authentication
200 OK

The initial 401 Unauthorized is a normal SIP authentication challenge.

The final 200 OK confirms that the registrar accepted the registration.

Use the registration interval accepted by the SIP server.

If your SBC cannot send REGISTER requests to the external provider, it cannot establish the normal Voyced connection described here.

7. Configure the SIP and Audio Settings

The Voyced connection should use standard telephone codecs.

Recommended:

Use a 20 ms audio packet time where configurable.

For DTMF, select RFC2833/RFC4733.

The SBC must handle media correctly between the two sides.

Use the media interoperability settings recommended by your SBC manufacturer.

Where possible, select G.711 on both sides to avoid unnecessary audio transcoding.

8. Configure Outgoing Number Formatting

Microsoft Teams commonly uses telephone numbers beginning with +.

For example:

+442012345678

Voyced expects the same number without the leading +.

Example:

442012345678

Configure a number translation rule on the SBC for calls going from Microsoft Teams to Voyced.

Example

A regular-expression-based SBC may use the following matching rule:

^\+([1-9][0-9]{7,14})$

Replacement:

$1

This removes the leading + while retaining the country code and telephone number.

The exact replacement syntax depends on your SBC.

The rule should only modify numbers matching the intended international format.

Do not remove the country code.

9. Configure Incoming Number Formatting

Incoming calls travel in the opposite direction.

Voyced delivers the call to the SBC using the SIP registration.

Microsoft Teams must then identify the receiving user or application by telephone number.

For the recommended Teams number format, the SBC should add a leading + when forwarding the incoming called number to Microsoft Teams.

Example:

A suitable number-matching expression is:

^([1-9][0-9]{7,14})$

Replacement:

+$1

This converts a digits-only international number to a number beginning with +.

The number sent to Teams must match the number assigned to the receiving Teams user or application.

If your SBC already performs this conversion correctly, do not add another rule.

10. Configure Caller ID

Your outgoing caller ID must be a telephone number authorised for presentation through your Voyced account.

Microsoft Teams may present the caller ID in a format such as:

+442012345678

The SBC can convert the number to:

442012345678

when sending the call to Voyced.

Check the following SIP identity information where used:

• From

• P-Asserted-Identity

• Remote-Party-ID

The exact headers used depend on your SBC and provider configuration.

For the first test, use the same authorised telephone number as your Voyced SIP account.

If you have several authorised outbound telephone numbers, configure the appropriate identity rules for each user.

Avoid presenting numbers you are not authorised to use.

11. Configure Incoming and Outgoing SBC Routing

Your SBC needs two call routes.

Outgoing Route

Incoming Route

The SBC must also recognise incoming SIP requests as belonging to the Voyced connection.

Use the registration information and the provider identification method supported by your SBC.

Do not route unknown external SIP requests into Microsoft Teams.

Save the routing configuration.

12. Add the SBC to Microsoft Teams

Open the Microsoft Teams admin center:

https://admin.teams.microsoft.com

Navigate to:

Voice → Direct Routing → SBCs

Click Add.

Enter:

For example:

Use your actual hostname.

The SIP Signalling Port must match the TLS listening port configured on the SBC's Microsoft Teams connection.

Port 5061 is a common choice.

The Maximum Concurrent Sessions value should reflect the capacity available for your connection.

Click Save.

13. Verify the Microsoft Teams SBC Connection

After adding the SBC, check the Direct Routing connection.

In the Teams admin center:

Voice → Direct Routing

Open the SBCs tab.

Locate your SBC.

Check:

• TLS connectivity

• SIP OPTIONS status

• Certificate status

• SBC availability

• Maximum concurrent sessions

The SBC should establish secure SIP connectivity with the Microsoft Direct Routing service.

Microsoft uses SIP OPTIONS messages to monitor SBC availability.

A healthy connection should show successful OPTIONS exchanges.

The SBC must respond correctly to OPTIONS messages received from Microsoft.

If the SBC is unavailable, check the certificate, DNS and network settings before continuing.

14. Assign Your Voyced Telephone Number to a Teams User

Once the SBC is connected, assign your Voyced number to a Microsoft Teams user.

In the Teams admin center:

1. Navigate to Users → Manage users.

2. Select the required user.

3. Open Account.

4. Under General information, click Edit.

5. Find Assign phone number.

6. Set Phone number type to Direct Routing.

7. Enter the user's Voyced telephone number.

8. Click Apply.

For example:

+442012345678

For Microsoft Teams, using the full international number with a leading + is recommended.

This is different from the number format sent to Voyced.

The SBC handles the conversion.

A telephone number should only be assigned to the intended Teams user or resource account.

15. Configure Additional Teams Users

If your Voyced account includes several telephone numbers, you can assign them to different Teams users.

Example:

For each user:

1. Confirm the Teams Phone licence.

2. Open Users → Manage users.

3. Select the user.

4. Assign the Direct Routing telephone number.

5. Save.

On the SBC, make sure the incoming called number is forwarded to Teams using the number format assigned to that user.

Several telephone numbers can share one Voyced SIP registration when they belong to the same SIP account.

Check that the SBC preserves the actual called DID for incoming calls.

16. Create a PSTN Usage Record

Microsoft Teams uses PSTN Usage records to control which voice routes users can access.

Navigate to:

Voice → Direct Routing

Select:

Manage PSTN usage records

Click Add.

Enter:

Voyced

Click Apply.

This creates a PSTN Usage record named Voyced.

It does not create a provider connection.

It is used to associate voice routes with voice routing policies.

17. Create the Voyced Voice Route

Navigate to:

Voice → Direct Routing → Voice routes

Click Add.

Enter:

For the dialled number pattern, configure the international destinations you want to permit.

A broad example pattern is:

^\+[1-9][0-9]{7,14}$

This matches numbers beginning with + and containing 8 to 15 international digits.

For example:

+442012345678

The pattern is used by Teams to decide whether the call should use the Voyced route.

The SBC removes the leading + before sending the call to Voyced.

For production use, configure more specific patterns if your organisation needs to restrict particular countries or number ranges.

Under SBCs enrolled, select your SBC.

Under PSTN usage records, select:

Voyced

Click Save.

18. Create a Voice Routing Policy

Navigate to:

Voice → Voice routing policies

Click Add.

Enter:

Add the Voyced PSTN Usage record.

Click Save.

The Voice Routing Policy controls which users can access the routes associated with Voyced.

For an organisation with multiple telephone providers, create separate policies where required.

Avoid changing the organisation-wide default policy unless you want that change to affect all eligible users.

19. Assign the Voice Routing Policy

Open:

Users → Manage users

Select the user who will make outgoing calls through Voyced.

Navigate to:

Policies

Find Assigned policies.

Click Edit.

Under:

Voice routing policy

Select:

Voyced Users

Click Save.

Repeat for each user who should use Voyced.

The user now has a policy that permits the selected outgoing route.

The user must also have a suitable Teams Phone licence.

20. Configure Dial Plans

Microsoft Teams uses dial plans to convert dialled numbers into the format used by its voice routing system.

For example, a user may enter:

02012345678

The Teams dial plan can normalise the number to:

+442012345678

The exact conversion depends on the user's country and dial plan.

For the initial setup, use international numbers with a leading +.

This avoids unnecessary national dialling conversions during testing.

If you need custom dialling rules:

1. Navigate to Voice → Dial plans.

2. Select an existing plan or create a new one.

3. Add the required normalisation rules.

4. Assign the plan to the relevant users.

5. Test the converted number.

The number reaching your SBC should normally contain the leading +.

The SBC then removes it for Voyced.

21. Configure Incoming Calls to a Reception or Call Queue

Microsoft Teams supports shared business numbers using resource accounts.

These can be linked to:

• Auto Attendants

• Call Queues

If your main Voyced number should reach a reception team rather than an individual user, create the appropriate voice application.

In the Teams admin center:

1. Navigate to Voice → Resource accounts.

2. Create a resource account for the reception service.

3. Assign the required resource account licence.

4. Assign the Voyced number as a Direct Routing number.

5. Create or select the required Auto Attendant or Call Queue.

6. Associate the resource account with that application.

Example:

The SBC must forward incoming calls to Teams using the number assigned to that resource account.

If the organisation uses several business numbers, configure a suitable destination for each.

22. Configure Simultaneous Call Capacity

Your connection's effective calling capacity depends on:

• Your Voyced service capacity

• Your SBC licence and session capacity

• Your Microsoft Teams Direct Routing configuration

• Any limits set on the SBC

For example:

These values are examples.

Configure limits according to the actual capacity of your service and equipment.

If the SBC also handles other telephone providers or PBXs, account for those sessions separately.

The concurrent session value configured in Teams should match the intended capacity of the Direct Routing connection.

23. Configure Firewall and Network Access

Your SBC communicates with two different services.

Microsoft Teams Side

Your firewall must permit the Microsoft Direct Routing signalling and media traffic.

Microsoft publishes the required IP ranges and port details.

Configure your firewall according to those published requirements and your SBC manufacturer's instructions.

Voyced Side

Your SBC must also permit the required RTP traffic for the Voyced connection.

The local RTP port range depends on your SBC.

If the SBC Is Behind NAT

Check:

• Public SBC IP address

• DNS record

• TLS certificate hostname

• SIP Contact information

• External media addresses

• Firewall rules

• UDP session handling

A correctly configured Microsoft Teams TLS connection does not automatically confirm that the separate Voyced SIP registration and audio connection are working.

Test both sides.

24. Configure Emergency Calling

Emergency calls require special attention in Microsoft Teams.

The available services and routing requirements depend on your country, user location and telephone provider.

Review your existing emergency calling arrangement.

In Microsoft Teams, the relevant areas may include:

• Emergency call routing policies

• Emergency addresses

• Network and location settings

• Dynamic emergency calling configuration

Confirm which provider and route will handle emergency calls.

If your organisation already has a working emergency calling service, preserve it until the new arrangement has been verified.

Do not assume that a normal international calling route provides correct emergency call handling or location reporting.

Testing Your Setup

1. Test Voyced SIP Registration

Open your SBC administration interface.

Locate the Voyced SIP connection.

Check the registration status.

Expected result:

Registered

The registrar should be:

sip.voyced.eu

If the SBC does not register, check the Voyced credentials and the provider-facing network connection.

Do not continue to inbound calling tests until registration succeeds.

2. Test Microsoft Teams SBC Connectivity

Open:

Teams admin center → Voice → Direct Routing

Locate your SBC.

Check:

• TLS connection status

• SIP OPTIONS status

• Certificate status

• SBC availability

The SBC should report a working connection to Microsoft Teams.

If the SBC is unavailable, inspect its TLS configuration and network connection.

3. Test an Outbound Call

1. Open Microsoft Teams.

2. Select Calls.

3. Open the dial pad.

4. Enter a full international telephone number.

5. Place the call.

For example:

+442012345678

Teams sends the call to the SBC.

The SBC should convert the destination to:

442012345678

The SBC then sends the call to Voyced.

Check:

• The correct voice route is selected.

• The SBC receives the call.

• The number is converted correctly.

• Voyced accepts the call.

• The destination rings.

• Two-way audio works.

• The correct caller ID appears.

4. Test an Incoming Call

1. Call your Voyced telephone number from an external mobile telephone.

2. Confirm the SBC receives the call.

3. Check that the SBC identifies the correct DID.

4. Confirm the called number is converted to the Teams format.

5. Check that Teams routes the call to the correct user or application.

6. Answer the call.

7. Check two-way audio.

Example:

If you have several Voyced telephone numbers, test each one separately.

5. Test Call Transfer and Voicemail

After basic inbound and outbound calls work:

1. Place an incoming call.

2. Answer in Teams.

3. Transfer the call to another Teams user.

4. Check that the transferred call connects.

5. Test unanswered calls and voicemail.

6. Test any configured Call Queue or Auto Attendant.

Depending on the call transfer destination, the SBC may need to handle additional SIP signalling.

6. Test Simultaneous Calls

Place more than one call at the same time, within the capacity of your Voyced service.

Check that:

• Both calls connect.

• Audio works in both directions.

• The SBC does not exceed its session limit.

• The provider accepts the required concurrent calls.

Troubleshooting

Microsoft Teams Cannot Connect Directly to Voyced

Microsoft Teams Phone does not support direct SIP REGISTER authentication to an external provider.

A Microsoft-certified SBC is required for Direct Routing.

The SBC must support SIP registration towards Voyced.

Do not enter sip.voyced.eu as the Teams Direct Routing SBC hostname. Microsoft Teams expects the hostname of your certified SBC, using a verified domain and trusted certificate.

SBC Is Not Available in Teams

Check:

• SBC hostname

• Microsoft 365 verified domain

• Public DNS

• TLS certificate

• TLS listening port

• Microsoft SIP proxy connectivity

• SIP OPTIONS messages

• Firewall rules

Also confirm the SBC is enabled in the Teams admin center.

SIP TLS Connection Fails

Check:

• The certificate matches the SBC hostname.

• The certificate has not expired.

• The certificate chain is trusted.

• The SBC supports Microsoft's required TLS settings.

• The correct listening port is configured.

• The firewall permits the connection.

SIP OPTIONS Fail

Microsoft Teams uses SIP OPTIONS to monitor SBC health.

Check:

• The SBC sends OPTIONS requests to Microsoft.

• Microsoft returns the expected response.

• The SBC replies correctly to incoming OPTIONS.

• The SIP Contact hostname is correct.

• DNS resolves to the correct SBC IP address.

OPTIONS failures can cause Teams to treat the SBC as unavailable for routing.

Voyced SIP Registration Fails

Check:

• SIP server is sip.voyced.eu.

• Username is correct.

• Authentication username is correct.

• Service password is correct.

• Registration is enabled.

• UDP port 5060 is used.

• DNS resolution works.

Confirm the SBC supports registration on its external SIP carrier connection.

401 or 407 Error

These responses indicate SIP authentication is required.

An initial challenge during registration may be normal.

If registration continues to fail, check:

• SIP username

• Service password

• Authentication realm

• Subsequent authenticated REGISTER requests

If an outbound call receives an authentication challenge, check the SBC's outgoing SIP authentication settings.

403 Error

Check:

• Voyced account status

• SIP authentication

• Caller ID authorisation

• Calling permissions

• Any account restrictions

If the response comes from Microsoft rather than Voyced, inspect the Teams routing and policy configuration.

Outbound Calls Do Not Reach the SBC

Check:

• User has a Teams Phone licence.

• User has a Direct Routing voice routing policy.

• PSTN Usage is configured.

• A matching voice route exists.

• The route includes the correct SBC.

• The SBC is enabled and healthy.

Also check the dialled number pattern.

Outbound Calls Reach the SBC but Fail

Check:

• SBC routes the call to Voyced.

• Voyced SIP registration is active.

• Destination number is correct.

• SIP authentication succeeds.

• Outbound caller ID is authorised.

• Calling capacity is available.

The SBC should send Voyced a destination such as:

442012345678

not:

+442012345678

Incoming Calls Reach the SBC but Not Teams

Check:

• Voyced registration

• Incoming DID identification

• SBC routing towards Microsoft

• Incoming number translation

• Teams telephone number assignment

• Resource account configuration

• TLS connectivity

The receiving Teams number must match the called number presented by the SBC.

Incoming Calls Reach the Wrong User

Check:

• Incoming called number

• SBC number translation

• Teams user number assignment

• Resource account number assignment

• Any extensions included in the number

A number-format mismatch can prevent Teams from finding the intended destination.

Incorrect Caller ID

Check:

• Teams caller ID configuration

• SBC From header

• P-Asserted-Identity

• Any caller ID translation rules

• Authorised Voyced telephone numbers

For the first test, use your registered Voyced number.

One-Way Audio

Check:

• Microsoft Teams SRTP connectivity

• SBC media configuration

• Voyced RTP connectivity

• Firewall rules

• NAT handling

• SDP media addresses

• Codec negotiation

The SBC must handle the media connection on both sides.

Successful TLS connectivity or SIP registration does not guarantee working audio.

Calls Disconnect After Approximately 30 Seconds

Check:

• SIP ACK delivery

• TLS signalling

• NAT handling

• Firewall timeouts

• SBC SIP timers

• Media negotiation

Inspect the signalling on both the Teams and Voyced sides of the SBC.

Calls Fail After Transfer

Check:

• SBC transfer configuration

• SIP REFER handling

• Re-INVITE handling

• Number formatting

• Transfer destination permissions

• Media negotiation

Use the SBC manufacturer's recommended Microsoft Teams Direct Routing interoperability settings.

Simultaneous Call Limit Reached

Check:

• Voyced service capacity

• SBC call capacity

• Microsoft Teams maximum concurrent sessions

• Current active calls

Make sure the configured limits match the available service capacity.

Reviewing Direct Routing Health

Open:

Teams admin center → Voice → Direct Routing

Use the health dashboard to review:

• SBC availability

• TLS connectivity

• SIP OPTIONS

• Certificate expiry

• Concurrent calls

• Network performance

• Call failures

For detailed SIP problems, inspect the logs on your SBC.

Check the call separately on the Microsoft Teams side and the Voyced side.

Final Tips

• Microsoft Teams Phone cannot register directly with Voyced.

• Use a Microsoft-certified SBC supporting external SIP registration.

• Configure the SBC's Microsoft connection using TLS and SRTP.

• Configure the SBC's Voyced connection using SIP registration to sip.voyced.eu.

• Use your Voyced telephone number as the SIP username.

• Use your Voyced service password for authentication.

• Use UDP port 5060 on the Voyced connection.

• Use G.711 A-law and μ-law for Voyced audio.

• Assign Teams Phone licences to the required users.

• Add the SBC under Microsoft Teams Direct Routing.

• Configure the required PSTN Usage, voice route and voice routing policy.

• Assign each Voyced number to the correct Teams user or resource account.

• Use international numbers beginning with + inside Microsoft Teams.

• Remove the leading + before sending calls to Voyced.

• Configure inbound DID conversion so Teams recognises the receiving number.

• Present an authorised caller ID.

• Check emergency call routing separately.

• Test both SBC connections, incoming calls, outgoing calls and audio.

Microsoft Teams Phone supports third-party telephone providers through Direct Routing.

With a suitable certified SBC, the correct Microsoft Teams licences, SIP registration and number translation, you can use your Voyced telephone service for normal inbound and outbound calls through Microsoft Teams.

Last updated: 27/10/2026

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All information provided is copyrighted and purely informative in nature. It is maintained by Voyced with the greatest of care using reliable sources only.
Given the fast evolution of the telecom sector, Voyced does not offer any guarantee about the accuracy and completeness of the information offered. 
We explicitly do not give anyone permission to use this information in any other way than to inform themselves about what (legal) requirements there may be and they need to comply with when registering Services and/or DIDs with Voyced.