Phone icon is missing in Teams app for Android

Dear Team,

I like teams very much and using it on my windows desktop and android smartphone and tablets. But for any strange reason, the telephone icon disappears very frequently! Sometimes it cames up again, but also disappears again. It's extremly unrelient and not predictable. It also happens very very much, that I got a message like "Changes applied, please restart app". Once I do that and have luck, the phone function is available, but in most cases not. I am really desperate... I guess something with the rights is corrupted in the backend servers. But as a private user (365 customer) I don't have access to tools like administrator board or so.... Does anybody of you have an idea? It's so annoying!
All the best and keep save, Martin