Tom Talks Microsoft Teams and Microsoft 365 Collaboration news and opinions

More Details on Microsoft Teams Direct Routing (Connect your own SBC for PSTN), including Direct Carrier Support


As I talked about on my 5 types of hybrid blog post, the only option to bring your own PSTN carrier to Microsoft Teams will be a model where you connect your own SBC directly to Microsoft Teams/Office 365. This has previously been referred to as “BYOT” (Bring Your Own Trunk) and “Direct Connect”, but has now been more formally announced as “Direct Routing”.

In a blog post accompanying announcements at Enterprise Connect Microsoft Confirmed

  • You will require a certified SBC from Ribbon (Sonus) or AudioCodes
  • Other SBC vendors may be added in the future
  • ThinkTel (Canadian carrier) will also support this scenario, the first direct carrier support to be announced
  • Microsoft Teams and Phone System licences

Direct Routing will be supported for Microsoft Teams only, not SfB Online. From Nikolay Muravlyannikov of Microsoft: “If you use a supported SBC (AudioCodes or Ribbon) with the CCE you can pair the same SBC, which is paired to CCE, to the Teams backend and migrate users from SFBO to Teams. It is a matter deploying Teams client and changing the voice routing on SBC and in our Cloud. Once all users migrated you can decommission the CCE [element of the box]”

Previously Microsoft have always talked about this scenario as the customer bringing the SBC, it’s exciting to see a carrier, ThinkTel being supported. I think as more carriers support Direct Routing this will be a very common customer deployment scenario, meaning the customer needs no local infrastructure.

Microsoft call out the following scenarios:

  • Easy Transition to Calling in Teams. By integrating with an existing PBX, pilot users can be moved to Calling in Teams while users remain on their legacy PBX. Eventually all users can be easily transitioned to Calling in Teams. The call traffic between these users during the transition stay within the organization.
  • Telephony System Inter/Op. While users are being transitioned to Calling in Teams, Call Center agents can continue to use their application. Direct Routing enables both use cases to coexist. The call traffic between call center agents and Teams users stay within the organization.
  • Support for Analog Devices. If an organization decides to move to Calling in Teams but has analog devices such as elevator phones or overhead pagers, these devices can be connected to Teams and Phone System via Direct Routing. Call traffic between analog devices and Teams users stay within the organization.

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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  • As always, a very enlightening blog with future trends cleary defined.

    But one thing provisioners have to remember, is when the lights go out and the fire bell sounds, there better be a good old POTS line in the building for the receprtion to talk to the emergency services with. And in a multitenant building, thats a fair amount of copper that still needs to be provisioned to serve the rules of Health and Safety. As another stand alone element that only gets used when something goes wrong, who makes sure its “always on”. Some countries have specific rules and provisions around emergency services lines, others just the provision of a dialable number.

    For a “lights still on” scenario, generating an emergency call from a Teams or SBO client, in the Direct Routing scenario, it will be the PSTN providers responsibility to populate the PSAP database with CLID/Address correlation for the emergency operator. Will the Microsoft provided public access routes be able to carry emergency calls? I ask that question because Vodafone provisioned SIP trunks do not permit static sites to pass emergency calls.. wheras the likes of Gamma do (populating the database(UK)).

    Another question that comes to mind, is certain carriers will only pass the CLID’s associated with their direct customer. What happens when your client account is set to forward calls to your mobile? What CLID presentation do you expect to see… your own number or the CLID of the caller trying to get hold of you?

    Again Tom, as always, a blog worth reading.

  • Thanks Tom – as ever very good update. I like the ThinkTel offer… these guys are always very much at the forefront when it comes to SIP and MS.
    I wonder when a few UK SIP providers will join with a similar service.

  • I wonder if the requirement for a static IP address that existed with CCE is still present with Direct Route. Any insight?

Tom Talks Microsoft Teams and Microsoft 365 Collaboration news and opinions