It depends on the casino website, some Casino websites allow registration with your phone number but in some cases when they didn't list your country codes among those available, you can use email.
Other casino websites make it compulsory to register using an email address, once you register, you'd be able to confirm using the activation link Wich will be sent to your email inbox although some emails doesn't go through but check the spam folder if it's there.
Other casino websites make it compulsory to register using an email address, once you register, you'd be able to confirm using the activation link Wich will be sent to your email inbox although some emails doesn't go through but check the spam folder if it's there.