SMS number?

[geddak]

Get started guide says:
Please note that you will be required to validate your email address when registering. You are also strongly advised to attach an SMS Phone Number to your account for security reasons. Although this is not required, it is the only way to recover loginserver passwords.

I looked under account settings but did not see anywhere to attach a number - could you let me know where that is?

Thanks,
Gedd