Our mission is to have a positive impact on 1 billion people by 2020. Being able to help charities around the world is an essential part of this goal. That's why we allow experts to display a default charity in which they donate their proceeds to. Please note that we don't pay the charity directly. You'll need to make that transaction after exporting the proceeds from your calls.
Then, after you've done some paid calls and you're ready to donate, you can go to your Account > Money > Export to PayPal. Two weeks following, the funds will be available in your personal PayPal account (sorry, we're working on making this faster), and you can donate whatever amount you wish to charity.