Voice LabTeams Phone

15 · ACS, Speech, Copilot

Calling SDK versus Call Automation

One is a person in a browser. The other is your service answering the call.

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Learn it in 5 minutes

The Calling SDK is the client for a human on a web or mobile page. Call Automation is the server API that answers, plays, recognizes, and transfers, and then receives events. A page that only uses the client SDK will not run an IVR.

If your app never sees the events, the call can be up while your code is asleep. Log the event type and the call id. Event Grid is one delivery path. A missed subscription looks like a broken prompt.

Use Call Automation when a bot answers, and make sure the events actually reach your app.

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Visual

ACS call automationAnswerPlayRecognizeDTMFTransferHang up
Events, not a phone tree hidden in a form. Calling SDK versus Call Automation still needs a human escape.
Pick one primarySDK · Human clientAutomation · Server IVR
You may use both, for different jobs. Counts in this drawing are teaching order, not customers.

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Worked example

Call Automation is the server-side IVR. The Calling SDK is a person in the browser.

  1. Human on a page Calling SDK
  2. Bot answers Call Automation
  3. Events Delivered to you
  4. Logs Call id

If it fails: The app never answers, so the caller hears ringing until the platform gives up.

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Quiz

Which description of Call Automation is accurate?

A colleague reports: The app never answers, so the caller hears ringing until the platform gives up. Where do you start?

Which description of Calling SDK is accurate?

Flashcards

Ecosystem

Glossary

  • Call Automation The ACS server-side calling API. Your app answers, plays, recognizes DTMF or speech, and transfers. You receive events. You do not drive a desktop click. Config: Subscribe to the events and time out the recognize step. Fault: The app never answers, so the caller hears ringing until the platform gives up.
  • Calling SDK The ACS client SDK for a human in a browser or a mobile app. Different from Call Automation, which is the server. Config: Pick the SDK if a person is on the page. Pick automation if a bot answers. Fault: A web page uses the calling SDK and nobody handles the server events.
  • Recognize step The Call Automation action that collects DTMF or speech. It needs a timeout and a path for ‘none of the above.’ Config: Map 0 to a human queue and test it. Fault: The bot repeats the prompt until the caller hangs up.
  • Azure AI Speech Microsoft’s speech-to-text and text-to-speech service. Copilot Studio and custom IVRs can use it. It is not emergency calling. Config: Choose a voice you are allowed to use and log the recognition result. Fault: The prompt language does not match the caller and every intent is unknown.

Sister technologies

Around the call: compliance recording, workforce management, emergency location, analytics, CRM screen pop, and an agent with a human escape. Each one has its own failure.

Config and troubleshooting

The app never answers, so the caller hears ringing until the platform gives up.

Cross-platform bridges

CUCM

Cisco CUBE is one of the SBC families named in this lab’s certification lesson. A certified release can be the Direct Routing SBC between Unified CM and Teams.

The tenant still needs a verified domain on the SBC FQDN, and the user still needs Teams Phone. The studio translator does not open a live AXL session. Confirm the current certified release before you build.

Webex

Teams Phone and Webex Calling are separate clouds. This lab does not describe a feature that registers a Webex Calling user into a Teams tenant.

A number move is usually a carrier port, a certified SBC, or a meetings interop product. Confirm before relying.

UCCE

Unified CCE stays the ACD until you migrate it. Microsoft’s contact-center articles name Connect, Extend, and Unify. They do not name a UCCE connector in the notes this lab cites.

Voice into Teams is still Direct Routing or Operator Connect. The routing script stays on the contact-center product you bought. Confirm the vendor’s current model. Source: https://learn.microsoft.com/en-us/microsoftteams/teams-contact-center.

Future hooks

Copilot Studio, Azure Communication Services, and Graph are later tracks in this lab. Treat any uncited limit as confirm before relying.

BridgesEcosystem

Sources and go deeper

Opened 2026-10. A row marked confirm did not open. Wikipedia is background. The Teams blog row is the community index.

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