SIP Join without seeing the User

We are hosting an Jitst-Meet on-Premise to switch from WebEx and a lot of Users are joining over their SIP-Phone, but they also log in with their Desktops to see the video-feed. In Webex every User gets a unique User-ID to Map the Sound to the User, but this feature dosent exist in Jitsi (?)

When we do this every User is listed twice in meet.

Is there a way to add a custom SIP-Header to tell meet that the user should join without displaying their name?

If by displaying their name you mean not show their representative thumbnails, you can set SIP users as hidden participants.

There is no such feature. Using the phone is not a good idea. Phone vs Web : better quality in web, 8kHz vs 44kHz, better error correction, better packet loss concealment…

Yes thats what I want to do. How can I accomplish this?