If you have an Airtel prepaid/post-paid phone number you can register on Airtel Xstream with your Airtel mobile number. You will have to be connected to the Airtel mobile data or Wi-Fi network.
If you are an Airtel DTH user, you will have to register on Airtel Xstream with the registered number of your Airtel DTH account. Airtel Broadband users can register on Airtel Xstream with the registered number of your Airtel Broadband account.