This call is going via that SfB federation gateway. What is happening here is, even though the Teams desktop and mobile clients don’t have SIP in them, they can connect to an Office 365 gateway to allow SfB federation. I found it wasn’t working for me in the web app, though logically it should. This works on the Teams desktop client (electron) and mobile app. You can input the password to join the Zoom meeting with the keypad. You can see in Teams it shows as a SfB federated contact, you can click the video call button, top right. Or you might need to take this SIP URI and paste it into a new chat in Teams then “search externally.” Otherwise, you may be given a selection of apps to choose from. If you have SIP: associated with Microsoft Teams, it will try to launch Teams

I’m not sure why they don’t put the SIP URI in the invite, maybe to allow click to launch SfB, possibly to avoid users confusing it with the standard non-SfB SIP URI in the invite. That link takes you to a web page that is just a button to launch a link to a SIP URI. If the zoom user has the feature enabled, at the very bottom of the invite, there is a link to “Join by Skype for Business.” In this example, I’ll use Zoom, but it will be much the same for any meeting platform that allows SfB SIP URI dial-in. The username is the prefix of the host’s room video address, in the format of For a scheduled meeting: (For example, For a Personal Room meeting: (For example, details here Dialling the Skype for Business SIP address from Microsoft Teams to join a Zoom Meeting.In Webex, there is a special format SIP URI you can dial, In Zoom, it is an option that the person inviting you to the meeting has to enable. How do Zoom and Webex meetings get a Skype for Business Join SIP URI? Unfortunately, most Teams users won’t know what “mode” they are in. This works via federation, so you need to be in Teams Only mode (which allows federation) and have federation enabled. You are probably better joining with the native client for those platforms. Still, interestingly you can dial this SfB SIP URI from Microsoft Teams to join the Zoom or Webex or another platform meeting. It’s not the slickest user experience and not something I would necessarily recommend. Many popular meetings platforms like Zoom and Webex have an option to add a SIP Address for Skype for business users to dial directly into the meeting from the Skype for Business client.

How to join skype meeting with skype id