Hi Uthayamurthy,
Welcome to Microsoft Community
I'm Regie S an Independent Advisor and Microsoft Teams user
When connecting in Bluetooth headset, Teams may not recognize the device, a way to solve this issue is undergo a restarting process.
You may also clear your teams cache on your android phone.
You can tap “Settings” > “Applications” > “Manage Applications” > find your Teams app from the app entry then tap it > tap "Storage" > Tap the "Clear Cache" button to delete the cache > return to Android’s home screen > restart your Teams app > sign in your account again and check the result.
Best Regards,
Regie S.