I've been looking for a way to ensure that the value entered in a Community Builder profile field is unique across the website, that is, making sure that no other user has entered the same value.

It's a field for a telephone number and it's important for our business that no two users enter the same telephone number. This might happen by coincidence, but more likely it would be one user attempting to create multiple accounts.

At the moment this field is validating with a regexp to ensure a German mobile telephone number is entered in the correct, international format:

Example: 0049234567890
Regexp: /^0049[1-9][0-9_]*$/i

I would need to continue to validate in this way, while making sure that the value is unique. This plugin would be worth paying the yearly professional membership dues, but I'd like to be sure that I'll be able to achieve the above.

One final question, is the validation through this plugin Ajax, server-side, or both?

Thanks for any help or feedback!

I'm really desperate for help on this one and would be grateful for any feedback ...