Custom client join meeting and access audio streams

Hi,

I'm trying to build an android app, which should be able to join a MS Teams meeting based on privided meeting invite link.

I've been testing the MS Graph API, which has functions to create calls, but is it possible to acces the live audio streams, for example with RTP, so the app can recive the meeting's audio stream and send an audio stream to the meeting?

Or are there other APIs to interact with the media stack?

I also looked into the Direct Routing for MS Teams. Is it possible to use it to join a MS Teams Meeting using a soft phone (SIP+RTP), or does this only work in combination with an PSTN?

Thank you for your support!