AI Voice Agent on Microsoft Teams Phone: Setup

Quick answer: Yes. Microsoft’s third-party voice agent integration for Teams Phone, generally available since 15 June, routes auto attendant or call queue calls to a resource account linked to the agent’s Azure app. It needs four Azure prerequisites, Microsoft supports only certified agents (one listed on 28 September 2026), and the agent’s transfers to external numbers fail.

If you are asking “can I connect a third-party AI voice agent to Microsoft Teams Phone?”, there are really three questions inside it. Which door does Microsoft support? What do you have to license and build to open it? And what happens when your agent is not the one vendor Microsoft has certified? This page answers all three from Microsoft Learn: the third-party voice agent setup article, the Azure Communication Services (ACS) Teams Phone extensibility documentation, the Direct Routing planning guide and the auto attendant and call queue licensing reference. Each page was read on 28 September 2026. The entities you will meet are Teams Phone, the Teams Phone Resource Account licence, Auto Attendant, Call Queue, Teams Phone Agent, ACS Call Automation, Azure Event Grid, Direct Routing, Operator Connect, Calling Plans, session border controllers (SBCs) and the Unify, Extend and Connect certification models.

Can I connect a third-party AI voice agent to Microsoft Teams Phone?

Yes. Microsoft’s setup article says it is written “for IT pros and Teams administrators who want to integrate certified third-party voice agent solutions and use them with Teams Phone Agent, Auto Attendant, and Call Queue.” Its change log lists the feature as generally available on 15 June. The page itself was last updated on 31 August 2026.

Under the hood, this is Microsoft’s Teams Phone extensibility (TPE) model, which the planning article calls the “Teams Phone Unify Integration model”. Your voice agent is an application built on Azure Communication Services Call Automation. Teams hands the call to it through a resource account, and the agent answers the call through ACS APIs. Teams keeps the phone number, the auto attendant and the call queues.

Microsoft’s planning article names three places the voice agent can sit:

• Teams Phone Agent or auto attendant routing. A menu option or routing rule sends the caller to the voice agent.
• Call queue via exception handling routing. Overflow, timeout or no-agents-available sends the caller to the voice agent instead of voicemail.
• Directly to a third-party voice agent. The number lands on the agent’s resource account with no Teams menu in front of it.

The ACS overview adds that a call queue in front of the agent “unlocks queue-specific behaviors that an Auto Attendant alone cannot express”. Its examples are overflow, timeout and no-agent-available routing, plus multi-hop transfer chains from a call queue to the voice agent and on to “another Call Queue, user, voicemail, or PSTN target”. That last item sits awkwardly beside the known issue on the Teams setup page (below): the ACS overview lists a PSTN target as a hop, while the Teams setup page says an external transfer from the voice agent fails. Test it rather than trusting either page. The planning article also says the agent can pass structured context (caller identity, intent, call topic, conversation summary and sentiment) to the Teams user who picks up next, where it appears in the Context Pane.

One sentence to keep: the supported way to put an AI voice agent in front of Teams Phone is to make the agent an Azure Communication Services application that Teams transfers calls to, not a device Teams dials.

Only certified voice agents are supported, and the list is short

This is where most projects go wrong. Microsoft’s Teams Unify Integration Model for voice agents page (last updated 17 August 2026) sets the support boundary in plain words: “Microsoft supports voice agents solutions only from the certified partners.” For problems, “you must contact your voice agents partner first”, and “Microsoft may reject support cases where a noncertified voice agents solution is used”.

When we read that page on 28 September 2026, its certified voice agent table had exactly one row: AudioCodes, linked to its VOCA conversational interaction center. The separate contact centre certification list is longer. It covers vendors certified under the Unify, Extend or Connect models, such as 8×8, Anywhere365, AudioCodes and Caseris. But those are contact centre certifications, not the voice agent list.

Certification matters in two different ways, and they are easy to mix up:

• Building is not gated. The TPE FAQ says “it’s not mandatory to be certified in order to start building solutions”. An in-house team can build an ACS voice agent and point a resource account at it.
• Support is gated. The voice agent page limits Microsoft’s support to certified partners. If you run an uncertified agent on this path, Microsoft may decline the case when a transfer breaks.

So before choosing a route, ask your vendor whether they appear on Microsoft’s certified voice agent list today, and check the list yourself. A vendor saying “we work with Teams” might mean any of the three routes below.

What you need before the first test call

The setup article lists four Azure requirements plus the Teams side. We built the table below as a minimum bill of materials for the smallest real deployment: one auto attendant with a press-1 option for the voice agent. It uses only what Microsoft’s own pages require.

Item	How many (minimum)	What Microsoft says it is for	Cost signal on Microsoft’s page
Teams Phone licence in the tenant	1	“At least one Teams Phone license to enable Teams Phone Agent, Auto Attendant, and Call Queue services”	Paid Teams add-on (price not on these pages)
Resource account for the voice agent, created with the agent’s Azure application ID	1	Links Teams to the agent’s app (New-CsOnlineApplicationInstance -ApplicationID)	Needs a Teams Phone Resource Account licence
Resource account for the auto attendant	1	Created, licensed and assigned to the auto attendant in the Teams admin center	Needs a Teams Phone Resource Account licence
Teams Phone Resource Account licence (SKU part number PHONESYSTEM_VIRTUALUSER)	2 (one per resource account)	“Each resource account must be assigned” one	“There is no longer any cost associated with acquiring” it, but you must still complete the purchase
Phone number on the auto attendant’s resource account	1 (optional per the setup page)	Needed for callers outside Teams: a service number, Operator Connect, Direct Routing or hybrid number	Depends on your connectivity route
Azure subscription	1	Hosts the ACS resource	Pay as you go
Azure Communication Services resource	1	Call Automation answers, plays, recognises and transfers	Per-minute ACS charges to the vendor or builder
Event Grid endpoint	1 subscription	Delivers the IncomingCall event to the agent’s webhook	Azure usage
Application endpoint hosting the agent logic	1	“must be reachable by Azure Communication Services events”	The voice agent vendor’s side

Total: 2 resource accounts, 2 zero-cost licences, 1 Teams Phone licence, 1 ACS resource and 1 Event Grid subscription, before a single minute of AI.

Microsoft’s two licence pages describe cost slightly differently. The licence page says there is no longer any cost. The resource account management page describes “a zero-cost allocation” and says more “can be purchased at a cost” if you need them. Check your own tenant under Billing, then Your products.

How to set it up, step by step

The setup article is clear that “the Teams portion of the third-party voice agent configuration is currently available through PowerShell only.” Here is the order Microsoft’s pages imply. Step 1 is yours, steps 2 to 4 belong to the voice agent vendor or your developers, and steps 5 to 8 belong to the Teams administrator.

1. Day one: confirm the support position. Open Microsoft’s certified voice agent list and write down whether your vendor is on it and on what date you checked. If they are not, read the Direct Routing section below before you build anything.
2. Stand up the Azure side. This means an Azure subscription, an ACS resource and an application endpoint for the agent.
3. Subscribe Event Grid to IncomingCall. ACS’s incoming call page says Call Automation “uses Event Grid subscriptions to deliver IncomingCall events”, usually to a webhook, and that subscription filters can route the event to specific applications.
4. Get the voice agent’s Azure application ID from the vendor or your app registration.
5. Create the voice agent’s resource account with New-CsOnlineApplicationInstance, passing that application ID. Set its usage location with Update-MgUser.
6. License it. Look up the PHONESYSTEM_VIRTUALUSER SKU with Get-MgSubscribedSKU and assign it with Set-MgUserLicense. Microsoft’s reference says you need a User Administrator or higher role to create and license resource accounts.
7. Point the auto attendant at it. Microsoft’s example builds a menu option with New-CsAutoAttendantCallableEntity -Type ApplicationEndpoint and the TransferCallToTarget action on DTMF Tone1. For a call queue, set the exception handling target instead.
8. Create, license and assign the auto attendant’s own resource account in the Teams admin center, and give it the phone number callers dial.

Finish state: a test call to the auto attendant number, press 1, and the agent’s webhook logs an IncomingCall event and answers. Then the agent hands off to a Teams call queue, and the queue representative sees the caller’s context in Teams. If you can reach that point, the integration works. Everything after that is about the agent’s behaviour, not the plumbing.

We have not run these PowerShell commands against a live tenant. They are Microsoft’s own example commands, cited as written, so treat them as the vendor’s reference rather than a tested script.

The documented failure: transfers to external numbers

This is the most useful sentence on Microsoft’s setup page, and it sits in the Known issues section: “When a call is transferred from Teams to a third-party voice agent, and the voice agent tries to conference or transfer an external phone number, the call fails.”

For an AI voice agent in front of a sales or service line, that matters more than it sounds. The common handoffs outside the building all hit it:

• the on-call technician’s mobile;
• an after-hours answering service;
• a partner’s or franchisee’s direct number;
• a sales rep who works from a personal mobile rather than the Teams client.

The known issue is narrower than “TPE cannot transfer externally”. The ACS capabilities page (last updated 23 July 2026) lists “Add external phone number to an ongoing call” and “Transfer the end user from ongoing 1:1 call to another agent or external phone number” as supported through Call Automation. The failure Microsoft documents is specifically the case where Teams transferred the call to the voice agent (the auto attendant and call queue path), and the agent then tries to send it back out to the PSTN. Handoffs to Teams destinations (an auto attendant, a call queue or a Teams user) are not affected by the known issue. Microsoft’s own pages are not consistent here: the ACS overview’s call queue example lists a “PSTN target” as a hop after the voice agent, and the Teams setup page’s known issue says that external transfer fails. As at 28 September 2026 the known issue was still listed.

We call the practical rule the one-external-transfer test: before you sign anything, make the agent transfer one live test call from your auto attendant to a mobile phone outside your tenant. If your call flow never leaves Teams, the known issue does not touch you. If it does leave Teams, the test tells you on day one instead of in production.

There is also a separate licensing trap on the same path. Microsoft’s licensing reference says that any auto attendant or call queue resource account that transfers calls to an external phone number needs more than the Resource Account licence. On Microsoft numbers it needs a funded pay-as-you-go Calling Plan licence or Communications Credits (or telco pay-as-you-go overage for New Commerce customers). On Direct Routing numbers it needs an online voice routing policy. On Operator Connect numbers Microsoft lists no extra requirement, but the same page warns that since 1 November 2025 outbound calls by auto attendants and call queues “may no longer be available depending on your carrier/operator”, so confirm with your operator. Since 1 November 2025, Calling Plan licences on resource accounts no longer cover on-behalf-of outbound PSTN calls.

The three routes compared

This is the page’s main asset. Every cell comes from the Microsoft Learn page named in the source table at the end, read on 28 September 2026. Where a cell is our own inference, it says so.

	Route A: Third-party voice agent on auto attendant or call queue	Route B: Full Teams Phone extensibility (CCaaS on ACS)	Route C: Direct Routing through a certified SBC (the Connect model)
Microsoft page	aa-cq-setup-third-party-voice-agents	tpe/teams-phone-extensibility-overview	direct-routing-plan; teams-contact-center (Connect tab)
Where the AI sits	Behind a Teams auto attendant, call queue or Teams Phone Agent, or directly on its own resource account	Answers calls to the resource account’s number itself via Call Automation	Outside Teams, reached over SIP through the SBC
Who owns the number	Teams (resource account)	Teams. The FAQ says only “Teams Phone service numbers assigned to resource accounts” are supported	Your carrier, trunked through your SBC
Licences named by Microsoft	1+ Teams Phone licence in the tenant, a Resource Account licence per resource account, plus ACS and Event Grid	Teams Phone licence for each human agent, Enterprise Voice, a Resource Account licence, and PSTN connectivity (Calling Plans, Operator Connect or Direct Routing)	Teams Phone licences for users. The Connect note says “The agent used contact solution doesn’t need a phone system license”
Microsoft’s support condition	Certified voice agent partners only (1 listed on 28 September 2026)	Certification recommended, not mandatory to build. For support, Microsoft’s contact centre page says it “supports Contact Center solutions only from the certified partners”	“Only Microsoft-certified SBCs are supported with Direct Routing”. The AI agent is not covered by SBC certification: Microsoft’s contact centre page limits support to certified contact centre partners
Handoff back to people	To Teams destinations with context. External conference or transfer fails (known issue)	AddParticipant or Transfer to ACS agents, Teams users or PSTN. Microsoft recommends AddParticipant over Redirect	SIP transfer or re-INVITE through the SBC. Our inference: behaviour depends on the SBC and the agent’s SIP stack, and it is not documented for AI agents on Microsoft’s Direct Routing planning page as at 28 September 2026
What you give up	External transfers from the agent. Setup is PowerShell only	Per the capabilities table: Teams convenience and compliance recording and call park are not supported, and forwarding rules, simultaneous ring and location-based routing are not honoured	Calls handled before Teams sees them do not show in Teams call history or queue reporting (our inference). Only certified SBCs are supported, and if the AI is sold as a Connect-model contact centre solution, Microsoft’s contact centre page limits support to certified partners
Best fit	An existing Teams auto attendant that needs a conversational front end, with a certified vendor	A contact centre vendor or in-house team building a full ACS agent desktop	An AI voice platform that speaks SIP but is not Teams-certified, or an organisation already running an SBC

Read across the rows and the pattern is simple. Routes A and B keep the number and the call inside Microsoft’s documented envelope, but both tie you to ACS, and on both Microsoft’s support depends on certification: a certified voice agent vendor on Route A, a certified contact centre partner on Route B. Route C is the only one of the three that does not need the AI agent to be built on ACS, and it moves the integration work into a certified SBC. It does not escape the certification question: Microsoft’s contact centre page applies the same “only from the certified partners” support boundary to contact centre solutions under all three integration models, Connect included.

What if my AI voice agent is not certified for Teams?

Then Route C, or a simpler variant of it, is the realistic answer, with one caveat up front: it changes who is supported, not whether certification matters. Microsoft supports Direct Routing only with certified SBCs, and its contact centre integration page says Microsoft “supports Contact Center solutions only from the certified partners” and “may reject support cases where a noncertified Contact Center solution is used”. An uncertified AI agent behind your SBC is your support problem and the AI vendor’s, not Microsoft’s. Microsoft’s Direct Routing page sends SBC issues to the SBC vendor first, and that vendor supports the SBC, not the agent behind it. Microsoft’s contact centre page lists three integration models: Unify (native ACS applications on Teams calling infrastructure), Extend (Teams client platform, Graph and Cloud Communications APIs, with the provider acting as a telephony carrier) and Connect (Microsoft-certified SBCs and Direct Routing). The Connect model is Microsoft’s documented way to connect a contact centre solution to Teams without living inside ACS, and it is the precedent for putting a SIP-based system in the call path.

In practice there are two shapes:

• AI first, Teams second. The carrier delivers the main number to the SBC. The SBC routes it to the AI agent’s SIP endpoint, and the agent transfers qualified calls back through the SBC to Teams users’ Direct Routing numbers. The Direct Routing plan lists related patterns: “Direct Routing for calls to third-party PBXs” and “Direct Routing for specialized routing scenarios”.
• Teams first, AI second. A Teams auto attendant or call queue sends a menu option to an external number that your voice routing policy sends over Direct Routing to the AI agent. That is an external transfer from a resource account, so the licensing reference applies: on Direct Routing numbers, the resource account needs an online voice routing policy.

Two constraints from Microsoft’s reference apply to both. First, “Transfers between Calling Plan, Operator Connect, and Direct Routing trunks aren’t supported” for auto attendants and call queues, so decide on one trunk type per call path. Second, “Direct Routing service numbers for auto attendants and call queues are supported for Microsoft Teams users and representatives (agents) only.”

If you are building the SIP side yourself, our walkthrough of a direct SIP AI voice agent with no Twilio in the path covers the trunk, codec and cutover checks. The guide to getting the caller’s number into your AI voice agent through SIP headers covers the caller identity that a Teams-first handoff can strip. If your phone system is a contact centre platform rather than Teams, see putting an AI voice agent in front of Genesys or Amazon Connect, or connecting an AI voice agent to 3CX, FreePBX or Asterisk for an on-premises PBX.

The honest DIY cost

You can do Route A yourself if you have a Teams administrator who is comfortable with PowerShell and a developer who can build on ACS Call Automation. Here is what it actually takes to run.

• Two sets of skills. Teams voice administration (resource accounts, licences, voice routing policies) and Azure development (ACS, Event Grid, a hosted webhook). These are rarely the same person.
• Two support queues. The TPE FAQ sends ACS SDK and Call Automation issues to Azure support and Teams or PSTN issues to Teams support. For an uncertified agent, Microsoft may not take the voice agent case at all.
• Per-minute ACS charges on top of your AI costs. The FAQ says TPE uses “Azure Communication Services regular business model” pay-as-you-go pricing. PSTN usage is not charged by ACS because it rides your Teams connectivity.
• A changing platform. Every ACS page we read carries a warning that ACS “is introducing breaking changes, and some services are being retired.”

Route C shifts the cost to SBC skills: certificates, a domain verified in Microsoft 365, SIP signalling FQDNs, and Microsoft’s recommendation of at least two media ports per concurrent call. If you already run Direct Routing, that cost is paid. If you do not, it is a project of its own.

Your situation	Route that usually fits	Why
Teams auto attendant already live, vendor on Microsoft’s certified voice agent list, all handoffs stay inside Teams	A	Supported end to end, and the known issue never fires
Same, but some handoffs go to external mobiles	A only after the one-external-transfer test passes, otherwise C	The known issue is documented for exactly this case
You are building your own contact centre desktop on Azure	B	The full Call Automation surface. Certification is optional to build but Microsoft’s support is limited to certified contact centre partners
AI vendor is SIP-capable but not Teams-certified, and you already run a certified SBC	C	No ACS dependency, and the SBC is already supported. The AI agent itself is not, so the agent vendor carries support
No SBC, no Teams voice admin, and the AI only handles outbound sales calls	None of the three	Outbound agents do not need to sit in front of your inbound Teams menu

The last row is the one people skip. An outbound AI sales agent, the kind Zian runs, calls leads directly and books meetings into a calendar or CRM. It does not need to intercept your Teams auto attendant at all. Zian does not publish a Microsoft Teams integration and is not on Microsoft’s certified voice agent list. Its published integrations are HubSpot, Salesforce, HighLevel and Zapier, plus an API. For outbound work, what matters is where the booked meeting and the call notes land. Our breakdown of why AI voice agent transfers to a human fail covers the live handoff problems that apply on any phone system, Teams included.

Frequently asked questions

Can I connect a third-party AI voice agent to Microsoft Teams Phone?

Yes. Microsoft documents a third-party voice agent integration for Teams Phone Agent, Auto Attendant and Call Queue, listed as generally available on 15 June in its Microsoft Learn setup article. The agent runs on Azure Communication Services and Teams transfers calls to a resource account linked to the agent’s Azure application ID.

Does my AI voice agent need to be certified by Microsoft to work with Teams?

To build, no: the Teams Phone extensibility FAQ says certification is not mandatory to start building. To be supported, yes: the Teams voice agents page says Microsoft supports voice agent solutions only from certified partners, and on 28 September 2026 it listed one, AudioCodes.

What licence does the voice agent’s resource account need?

A Microsoft Teams Phone Resource Account licence, SKU part number PHONESYSTEM_VIRTUALUSER, assigned to each resource account. Microsoft’s licence page says there is no longer any cost for it, though you must still complete the purchase. The tenant also needs at least one Teams Phone licence.

Why does my AI voice agent fail when it transfers a Teams call to a mobile number?

Microsoft lists it as a known issue: when Teams transfers a call to a third-party voice agent and the agent tries to conference or transfer an external phone number, the call fails. Transfers to Teams destinations such as a call queue or a Teams user are not affected. Microsoft’s ACS overview lists a PSTN target as a possible hop after the agent, so the two pages disagree: test one external transfer before you commit.

Which Azure resources do I need for a Teams third-party voice agent?

Four, per Microsoft’s setup article: an Azure subscription, an Azure Communication Services resource, a configured Event Grid endpoint that delivers the IncomingCall event, and an application endpoint hosting the agent logic that Azure Communication Services events can reach.

Can I use Direct Routing instead to put an AI agent in front of Teams?

Yes. Microsoft’s Connect integration model uses certified session border controllers and Direct Routing to connect contact centre solutions to Teams. An SBC can route the number to a SIP-capable AI agent first. Microsoft supports Direct Routing only with certified SBCs, and its contact centre integration page says Microsoft supports contact centre solutions only from certified partners, so an uncertified AI agent is supported by its vendor, not by Microsoft. Auto attendants and call queues also cannot transfer between Calling Plan, Operator Connect and Direct Routing trunks.

Can I set up the Teams side in the Teams admin center?

Only partly. Microsoft says the Teams portion of the third-party voice agent configuration is currently available through PowerShell only. The voice agent’s resource account is created with New-CsOnlineApplicationInstance using the agent’s application ID. The auto attendant’s own resource account can then be created, licensed and assigned in the Teams admin center.

Where every figure on this page comes from

Figure	Who published it	Link	Date read
Third-party voice agents generally available on 15 June; page last updated 31 August 2026; PowerShell only; 4 Azure requirements; external transfer known issue; PHONESYSTEM_VIRTUALUSER SKU	Microsoft Learn (Teams)	aa-cq-setup-third-party-voice-agents	28 September 2026
3 places the voice agent can sit; context fields passed on handoff	Microsoft Learn (Teams)	aa-cq-plan-third-party-voice-agents	28 September 2026
1 certified voice agent provider listed (AudioCodes); support limited to certified partners	Microsoft Learn (Teams)	teams-voice-agents	28 September 2026
At least 1 Teams Phone licence; 1 Resource Account licence per resource account; external transfer licensing; 1 November 2025 change; trunk-mixing and Direct Routing service number limits	Microsoft Learn (Teams)	aa-cq-reference-prerequisites-licensing	28 September 2026
Resource Account licence has no cost	Microsoft Learn (Teams)	virtual-user	28 September 2026
Zero-cost allocation, extras at a cost	Microsoft Learn (Teams)	manage-resource-accounts	28 September 2026
2 Teams Phone entry points (auto attendant and call queue); TPE licence prerequisites	Microsoft Learn (Azure Communication Services)	teams-phone-extensibility-overview	28 September 2026
Only Teams Phone service numbers supported; certification not mandatory to build; ACS pay-as-you-go model	Microsoft Learn (Azure Communication Services)	teams-phone-extensibility-faq	28 September 2026
Supported and unsupported capabilities (external transfer, recording, park, forwarding)	Microsoft Learn (Azure Communication Services)	teams-phone-extensibility-capabilities	28 September 2026
3 PSTN connectivity options; 105 Operator Connect operators	Microsoft Learn (Azure Communication Services)	teams-phone-extensibility-connectivity-cost	28 September 2026
IncomingCall delivered through Event Grid	Microsoft Learn (Azure Communication Services)	incoming-call-notification	28 September 2026
Only certified SBCs supported; at least 2 media ports per concurrent call	Microsoft Learn (Teams)	direct-routing-plan	28 September 2026
3 integration models (Unify, Extend, Connect); contact centre certified list; support limited to certified contact centre partners	Microsoft Learn (Teams)	teams-contact-center	28 September 2026

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