Removing phone # as required field on customer registration form

[obcbeatle]

Hello:

 

I would like to remove the phone # as a required field on customer registration form (but keep the phone number field, as optional). I saw a post re: same, but it's over 4 years old and I didn't follow how the user made the change. Can you point me to somewhere else in the forums, or if you have done this, tell me how to make the change? If it matters, I'm running v2.2 RC2a with all the security patches applied per the security forum. Thanks!