Microsoft Teams spoofing on mobile client?

We are an organization that has no telephony integrated with Teams. We've ever had dialing numbers connected/voip integrated and our Teams is for internal chat/channel/meetings only. User 1 reached out to me after hours saying she was contacted by user 2 wanting to know why user 1 called her on Teams. Call listed on user 2's phone as she had the mobile version of Teams installed on iPhone and sent User 1 a screenshot of the missed Teams call. User 1 didn't initiate the call and confirms her work from home computer was locked. She lives alone and was away from home at the time of the call. I checked user 1's call log in Teams admin site and last call she made was 2 days ago. Not sure where to go with this. Is spoofing a Teams call a thing?