Finding out OTP without closing the APP

I had the same problem but I finally find out the solution. This is how you must start working. First open your SMS app. Do not close the app but press the return button. Now, you open the APP in which you want to work. Now, your SMS app is not appear on the screen but it will be there at the downside margin. When they ask your Mobile number and OTP, and you hear the SMS sound, just press the left side button on the downside of the mobile. You will know the otp and you can go forward filling up your app.