Cannot add members to Teams Video Call & Paritipants cannot unmute themselves

Hi julian0204,

Thank you for your posting, my pleasure to assist you. We also appreciate for the detail information you collected.

1. No, you could not invite guest if you haven't added them prior during the meeting, that's why you couldn't get any search result. That button is the button right beside the chat one, you have this one, so no worries.

To add your guest, you need to first add it, you could refer to this document.  (remember to enable guest access in Teams which also stated at document).

After complete the step one, you could proceed the next one:

2. Could we confirm with you only guests has this symptom? You could let those guests to make sure the audio device is plugged in also make them do the test call first. 

In addition, let those guest user do this if they have teams:

• Go to File Explorer, and type in %appdata%\Microsoft\teams

• Once in the directory, you’ll see a few of the following folders:

-         From ‘Application Cache’, go to Cache and delete any of the files in the Cache location. “%appdata%\Microsoft\teams\application cache\cache”

-         From ‘Blob_storage’, delete any files that are located in here if any. “%appdata%\Microsoft\teams\blob_storage”

-         Within ‘Cache’, delete all files “%appdata%\Microsoft\teams\Cache”

-         Within ‘databases’, delete all files “%appdata%\Microsoft\teams\databases”

-         Within ‘GPUCache’, delete all files “%appdata%\Microsoft\teams\GPUcache”

-         Within ‘IndexedDB’, delete the .db file “%appdata%\Microsoft\teams\IndexedDB”

-         Within ‘Local Storage’, delete all files “%appdata%\Microsoft\teams\Local Storage”

-         Lastly, from ‘tmp’, delete any file “%appdata%\Microsoft\teams\tmp”

Restart Teams and test on their side.

3. That's a bit complicated since there is no extra information given, if you are referring to login to skype, the credentials(Account ID and password) should be as same as your Teams.

In addition, it depends on your mode, if your organization has been Teams only mode, once you access the skype, you could not use any function for the skype for business: 

Please let us know if this could help you.

Kind Regards,

George