BuddyPress.org

Greetings,
I have a very simple requirement where I would like to have a mobile/phone number field in the registration form which is doable by adding custom registration fields in Buddypress but, I want the mobile/phone number to have a unique meta key value so that no user can create a second profile with same mobile/phone number.

Just like email has a unique meta key so that the user can have one account with one email ID, similarly, I would like to have mobile/phone number to be associated with only one profile.

I don’t want to implement any 3rd party plugin for registration like Ultimatemeber etc as it ads a lot of pages too. I would like to have a small snippet or function to attain this.

Any help would be highly appreciated.
Waiting for the reply!
Regard
RW