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Understanding Microsoft Azure Communication Services (CPaaS)


Azure Communication Services is Microsoft’s CPaaS (Communication Platform as a Service) platform that is also the platform that powers Microsoft Teams, it became generally available in March 2021.

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Azure Communication Services provides libraries for mobile apps, desktop, and web, allowing developers to add the following to their applications.

  • Voice and Video Calling – Make and receive voice and video calls over IP including interop to Microsoft Teams (Teams interop still in preview)
  • Chat – Enable One-to-One or Group Chat functionality
  • SMS – Add SMS to applications and connect with users that prefer mobile communication.
  • PSTN Telephony Voice Calling – Allow for users to interact with a traditional telephone number, facilitated by PSTN (Public Switched Telephone Network) for voice calling.

Example scenarios include:

  • SMS reminders for appointments and follow up surveys
  • Web Chat
  • B2C VoIP and Video calling from websites and apps, for example, patient to doctor in healthcare or buyer to the retailer, in these scenarios the “B” users could be using Microsoft Teams

Azure Communication Services interoperability with Microsoft Teams

As of December 2021, this ability is now generally available. This enabled developers to build applications on ACS and have some users connect using the custom application/ACS and other users connect using Microsoft Teams. Where is this useful? Here is an example; A Video portal embedded into a healthcare website, the patient gets a great voice and video experience in the browser, all branded as the healthcare provider and the doctor can connect to the session with Teams, just like they connect to any other call or meeting.

The organization’s users and IT benefit from the security, familiarity, and capability of Teams, and external users, maybe customers or partners, can enjoy a custom communication experience on a web or mobile app.

I expect to see some really powerful B2C scenarios build on ACS where the organization’s users simply use Teams to connect.

Documentation: ACS Teams interoperability

ACS overview sessions from Microsoft Ignite

Azure Communication Services PSTN Coverage and SIP interface

Currently, SMS and PSTN Phone numbers availability is restricted to paid Azure subscriptions that have a billing address in the United States and Communication Services resources that have a US data location, much less than many other CPAAS players.


Azure Direct Routing, bring your carrier to Azure Communication Services

Exciting news on the Azure Communication Services Front, you can now connect your own PSTN carrier or interop with an existing PBX via a variant of the same Direct Routing Microsoft Teams

For those not familiar with ACS, it’s Microsoft’s CPaaS (Communication Platform as a Service) platform that is also the platform that powers Microsoft Teams, more details here.

Microsoft offers Azure Cloud Calling for Azure Communication Services, the ability to buy phone numbers and PSTN serviced directly from Microsoft. This option means you deploy no infrastructure and it’s an end-to-end cloud service from Microsoft, but right now only for US numbers and outbound calling only. Here are the current call costs for Azure Cloud Calling

Azure Direct Routing for ACS is different from Microsoft Teams Direct Routing, but the concept and approach are basically the same.

With this option, you can connect legacy on-premises telephony and/or your PSTN carrier of choice to Azure Communication services.

It provides PSTN calling capabilities to your Communication Services application to cover anywhere in the world.

You or your partner need to deploy a physical or virtual SBC and connect it to Azure Communication Services.

The following codecs are supported: SILK, G.711, G.722, G.729

Media bypass is not yet supported by Azure Communication Services. Early media is not supported by a web-based client.

Not Azure previews are provided without a service-level agreement, and not recommended for production workloads.

Azure Direct Routing Pricing

Pricing is different to Teams where you buy a user license for Teams Phone and then just pay the PSTN Carrier for the minutes. In ACS the whole service works on consumption/Pay Per minute/Per SMS/Per chat message etc., so even with Direct Routing, you are paying per minute for the service used, as well as paying your PSTN carrier.

Sessions/legs to/from an SBC cost $0.004 per minute on the ACS side.

LinkedIn and Avaya integrate with Azure Communication Services

LinkedIn (a Microsoft company) is using ACS to allow users to quickly set up and join video meetings within LinkedIn’s messaging environment without needing to sign in anywhere else or download anything.

Second, Avaya, who would be considered a competitor to Microsoft in the UCaaS space has announced:

Avaya OneCloud CPaaS (Communications Platform as a Service) now integrated with voice, video, chat, and SMS capabilities of Microsoft Azure Communication Services
They also made further partnership announcements:

  • Globally expanding the availability of Avaya OneCloud CCaaS (Contact Center as a Service) hosted in Azure
  • Avaya OneCloud CCaaS natively integrated with Microsoft Teams via the Microsoft Teams Connected Contact Center Certification Program
  • Avaya OneCloud CCaaS integration with Microsoft Dynamics 365
  • Avaya SBCs is now certified for Microsoft Teams Direct Routing
  • Avaya has a strong contact center base, so interesting seeing them go down the Microsoft Teams certified contract center route.

Microsoft Customer Story-LinkedIn gives members fast, convenient video meetings with Azure Communication Services

Avaya and Microsoft Announce Integration of Microsoft Azure Communication Services with Avaya OneCloud™ CPaaS


About the author

Tom Arbuthnot

A Microsoft MVP and Microsoft Certified Master, Tom Arbuthnot is Founder and Principal at Empowering.Cloud as well as a Solutions Director at Pure IP.

Tom stays up to date with industry developments and shares news and his opinions on his, UC Today Microsoft Teams Podcast and email list. He is a regular speaker at events around the world.

  • Tom Talks Microsoft Teams and Microsoft 365 news and opinions