It is a security feature to protect your account from unauthorized users. You will be asked to enter an OTP every time you change your device. The OTP will be sent to your registered mobile number and is just a one-time activity.
If in case you do not have access to your registered mobile number, you can get the mobile number updated by sending us an alternate number along with any ID proof of yours to email@example.com.
Note: The OTP is sent instantly on most occasions but sometimes there might be a delay due to bad network. In such a case, we request you to try again after 15 minutes.