What it does

Microsoft is retiring the standalone Azure Communication Services capabilities that Contact Center uses for voice, SMS and WhatsApp, with end of service on 30 September 2028. Teams Phone extensibility becomes the strategic voice platform, and SMS and WhatsApp move to Twilio or Infobip. This is the plan-and-migrate path for anyone currently on ACS.

Key facts

• Announced 23 September 2026; affected capabilities stay fully supported until 30 September 2028
• Affected: voice via ACS Direct Offer or ACS Direct Routing, SMS via ACS, WhatsApp via ACS
• Not affected: voice already on Teams Phone extensibility, SMS via Twilio or Infobip, WhatsApp via Twilio
• From 30 September 2026, tenants without an existing ACS resource can't acquire or port numbers into ACS at all. Existing ACS customers keep acquiring and porting throughout the retirement period
• Three voice destinations: Teams Calling Plan (Microsoft-managed PSTN), Teams Direct Routing (keep your carrier and SBC), Operator Connect (certified carrier manages connectivity)
• Direct Offer → Calling Plan has no automated path. You raise a ticket on the Microsoft telephone number services portal and support moves the numbers manually
• Calling Plan migration isn't available everywhere — ACS numbers in Asia Pacific can't be migrated to Calling Plan at all
• Every service number used by Contact Center needs a Teams resource account with a licence, same as any Teams Phone number
• You can't have the same SBC FQDN registered against ACS Direct Routing and Teams Direct Routing at once
• ACS and Teams use different media address ranges — firewall rules need reworking, not copying

When to use / skip

Nobody gets to skip this if they're on ACS. What you do get to choose is timing, and two years is less runway than it sounds once you factor in number porting, carrier negotiation and a UAT cycle per channel. Start the inventory now and the migration when you've got a quiet quarter. If you're scoping a new Contact Center deployment, don't put ACS voice, SMS or WhatsApp in the design at all — go straight to Teams Phone and Twilio/Infobip.

Configuration decisions

• Voice destination: Calling Plan if you want Microsoft to own the PSTN and have no carrier attachment; Direct Routing if you've got SBCs and a carrier contract worth keeping; Operator Connect if you want carrier-managed connectivity without running SBCs yourself
• Cutover vs coexistence (Direct Routing): full cutover means removing the FQDN from ACS and waiting for propagation, with downtime in the gap. Coexistence needs a second FQDN or alias and a certificate covering both
• Carrier strategy (Operator Connect): ask your current carrier to move the ranges to its Operator Connect service, or port to a different participating operator. Keeping the carrier is far less painful
• Messaging provider: Twilio or Infobip for SMS, Twilio for WhatsApp. Compare geographic coverage, number portability and what you already have commercially before splitting across two providers
• Number origin tracking: record for every number whether it was acquired from ACS or ported in. Get this wrong and Teams counts a ported number against your acquisition quota
• Phasing: which queues, number ranges and countries go first, and how long the two configurations run side by side

Gotchas

• The 30 September 2026 number restriction is the near-term deadline, not 2028. If a client has Contact Center but no ACS resource yet, they lose the ability to provision ACS numbers within days. That reshapes any in-flight implementation plan that assumed ACS numbers were available.
• A global Teams voice routing policy will quietly hijack Operator Connect calls and push them down a Direct Routing trunk. Use targeted custom policies for the accounts that actually need Direct Routing, and check this before you blame the carrier.
• Migration tickets run Eastern Time business hours. Number moves aren't self-service and aren't fast. Build the support turnaround into the plan rather than promising a date to the business.
• SMS and WhatsApp migrations are provider changes, not config changes. Templates, consent records, carrier registration and number provisioning all move to Twilio or Infobip and are managed there. Budget for re-approval of WhatsApp templates; it's the step that slips.
• Don't decommission the ACS resource on cutover day. Keep it until you've watched inbound routing, transfers, voicemail and emergency calling behave for a full business cycle. Releasing numbers early is the one mistake you can't undo.
• Emergency addresses don't come across. Every migrated number needs its emergency location configured in the Teams admin center, and in several jurisdictions that's a regulatory obligation rather than a nicety.

Consultant notes

• Scope this as a programme, not a change request. Voice, SMS and WhatsApp are three separate migrations with three different providers, three sets of testing and, in most tenants, three different people who own them. Clients hear "2028" and put it in a backlog; the honest framing is that number porting alone can eat a quarter.
• The licensing conversation lands harder than the technical one. Teams Direct Routing and Operator Connect both need a Teams Phone licence per user or resource account, which for an ACS shop is usually a new line item nobody budgeted. Get the seat count in front of the sponsor early.
• Expect the SBC work to sit with a network team that has no stake in the Contact Center project. Certificates, SANs, firewall ranges and the FQDN collision all land on them, and none of it is in your gift. Identify that team at kickoff or you'll find out about the dependency in UAT.
• Watch for clients who adopted ACS because Teams Phone wasn't available in their region. Calling Plan availability in a country doesn't guarantee a given ACS number can be migrated, and Asia Pacific is already called out as unsupported. Check number-level eligibility per country before you commit to a path in the design.

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Revisit as the 30 September 2026 number-acquisition cut-off passes and Microsoft publishes further migration tooling.