The reason why you have to provide your valid email and phone number on file with AWS when registering for Amazon EC2 is quite simple. This is so that Amazon can be able to contact you when they need you. Verifying your phone number during the registration process for Amazon EC2 takes only a few minutes. You will receive a phone call as you register and enter your pin number on your phone. This ensures no one can hack your account once it is up and running.
With the advent of the internet, getting a secure account online is very important. Amazon takes your security seriously, and that is why they have to send you a PIN number in order to complete the registration process. Moreover, this is a good way of ensuring you are a human and not a computer trying to get unauthorized entry into their database.