Incoming Teams Calls on iPhone Automatically Answered Current Cell call automatically put on hold

I have a user with an iPhone that is reporting when he receives an incoming Teams call in the Teams app while he is in a cell call or other meeting app, the Teams call automatically answers and the ongoing call is automatically put on hold. 

I have not been able to locate any settings in Teams app, Teams admin, or on the iPhone that would change this setting or prevent this from happening. 

Anyone have any ideas?