Paying friends with your phone means you can send, request, and receive payments from your friends using your phone - and it's quick, easy and completely secure. You don't need to know the recipient's account number - you can just use their phone number.
The service works through Bizum, a system that's compatible with most other Spanish banks and which connects customers' bank accounts linked to their mobile phone number (you don't need to know any IBAN numbers to send money).