Any bank can join.. if they meet the requirements. https://www.bankgirot.se/en/about-bankgirot/participant-requirements-for-the-settlement-and-clearing-systems

Any bank can join.. if they meet the requirements. https://www.bankgirot.se/en/about-bankgirot/participant-requirements-for-the-settlement-and-clearing-systems/Payments-in-real-time/ https://www.bankgirot.se/en/about-bankgirot/participant-requ... There are plenty of legal regulations to wade through to join, but it's not impossible and the requirements are publicly available.