Dynamics 365: from ACS Direct Routing to Teams Direct Routing

What is happening?

On 23 September 2026, Microsoft announced that Azure Communication Services (ACS) is being retired as a standalone service. For Dynamics 365 Contact Center, this affects voice via ACS, both numbers bought from Microsoft (Direct Offer) and your own operator via ACS Direct Routing, as well as SMS and WhatsApp via ACS.

Voice that already goes via Teams Phone is not affected. Microsoft calls Teams Phone extensibility the strategic voice platform for Contact Center. Existing ACS configurations keep working, at the current service level, up to and including 30 September 2028. Since autumn 2026, new ACS customers cannot acquire or port in numbers.

Dynamics 365 Contact Center itself continues to work after 2028. What stops working is voice, SMS and WhatsApp that still go via ACS.

Three ways forward

Microsoft sets out three paths for voice, depending on how you are connected today:

Today	Way forward	Suits you when
ACS numbers from Microsoft (Direct Offer)	Teams Calling Plan	You want Microsoft to remain your operator.
ACS Direct Routing	Teams Direct Routing	You want to keep your operator, numbers and SBC, or you have advanced routing and failover routes.
ACS Direct Routing	Operator Connect	You want an operator in Microsoft’s programme to manage the connection and the SBCs.

This guide covers the path from ACS Direct Routing to Teams Phone with Direct Routing. Our offering for telephony for Dynamics 365 Contact Center is described on a separate page.

How ACS and Teams Direct Routing differ

Area	ACS Direct Routing	Teams Direct Routing
The SBC connects to	The ACS resource in the Azure portal	Teams admin center and Teams PowerShell
Numbers in Dynamics	Added or imported in Dynamics	Assigned to a Teams resource account (one per number) and synced to Dynamics
Licences	ACS usage charges	Teams Phone for users and a free licence per resource account
SBC domain name	The same name cannot be in ACS and Teams at the same time	During coexistence a new name is used, and the certificate must cover both, unless you use one certificate per name
Future	Retired on 30 September 2028	Microsoft’s direction

The same AudioCodes SBC can often be used, if the model and software version are on Microsoft’s list of SBCs certified for Teams and the capacity is also sufficient for the contact centre.

Take inventory first

Most of the work lies in knowing what you have. Go through:

• Numbers: all numbers with type, country and operator, and whether they come from ACS Direct Offer or Direct Routing.
• Queues and routing in Dynamics: which numbers belong to which workstreams and queues, IVR menus and Copilot agents, opening hours, where calls go when the queue is full, and voicemail.
• Routing in the SBC and ACS: voice routes, policies and number ranges.
• Dependencies: other systems and external IVRs that use today’s routes, and whether data is passed with the call into Dynamics.
• Recording and transcription: what is recorded and how long it is kept. Data in ACS can be exported during the transition period but is deleted after the retirement.
• The SBC: model, software version, capacity, domain name, certificate and firewall rules.
• Licences and roles: Teams Phone, resource accounts and Dynamics, and who has admin rights in Teams and Azure.
• Emergency addresses for every number.
• The operator: contracts and dependencies.
• SMS and WhatsApp via ACS: moved separately, SMS to Twilio or Infobip and WhatsApp to Twilio.

Full cutover or coexistence

Area	Full cutover	Coexistence
Domain name	The same name is removed from ACS and added to Teams	A new name for Teams while ACS stays in place
Certificates	Unchanged	Must cover both names
Risk	Downtime while the change propagates	More configuration, but numbers can move in stages and ACS remains as a fallback

For a contact centre that cannot afford downtime, we prefer coexistence: numbers move one group at a time, and ACS stays until the new route has been tested.

Test before you move

Start with a test number or a non-critical number, and test:

• the encrypted connection and signalling between the SBC and Microsoft
• inbound calls to the right queue and agent
• outbound calls with the correct caller ID
• transfer, consultation and voicemail
• recording, transcription and IVR menus
• data that should follow the call into Dynamics
• emergency calling, where relevant

After the move, monitor call quality and check that the SBC shows as active in Microsoft’s Direct Routing health dashboard.

A sensible order

• Take inventory of numbers, queues, routing, SBC and licences.
• Confirm licences and local regulations.
• Design the target architecture and choose full cutover or coexistence.
• Run a pilot with a test number.
• Move production in a low-traffic maintenance window, one number group at a time.
• Validate, monitor and decommission the ACS configuration last.

Do not end ACS billing or release any numbers until everything is stable.

Risks to watch

• Downtime during a full cutover, while the change propagates.
• The firewall: ACS and Teams may use different IP address ranges for media.
• A global routing policy in Teams can send the wrong calls to the Direct Routing trunk. Use targeted policies.
• Number porting can be rejected by the previous operator, and it is hard to reverse.
• Emergency calling from Contact Center is poorly documented outside the US and needs testing.
• Microsoft’s documentation changes quickly. Rely on pages updated after the September 2026 announcement.

Last updated 14 October 2026.