Teams is unable to handle the additional device very well. IOS is fine natively but teams seems to need about 30 seconds to acknowledge and allow you to switch. During this time the audio is completely cut off.
Yes this seems to be an issue with the Teams Application taking time to switch the devices call control if the call comes on the IPhone native device to regular Microsoft Teams Application. We have seen issue on even Android devices.
Microsoft is working on the same. In case you want to submit your feedback to the product group I would recommend you to submit the same here.
