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Azure Direct Routing Preview, 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

Azure Direct Routing for ACS is different to 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.



Right now only one SBC vendor is supported, and it also happens to be the one Microsoft owns, Metaswitch. More vendors will be on the supported list in due course.

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 licence 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.

Azure Communication Services direct routing legs will not be charged until 08/01/2021.


Microsoft Documentation Reference:

Azure Direct Routing Concept

Azure Communication Services direct routing configuration

List of Session Border Controllers certified for Azure Communication Services direct routing

Azure direct routing infrastructure requirements

ACS Pricing

About the author

Tom Arbuthnot

A Microsoft MVP and Microsoft Certified Master, Tom Arbuthnot is Principal Solutions Architect at Microsoft Collaboration specialists Modality Systems.

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

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Tom Talks Microsoft Teams and Microsoft 365 news and opinions