SiX Payment - Worldline SaferPay gateway
This is mostly used in countries around the world, "SaferPay".
In Europe and Asia countries too as SiX Payment - Wolrdline is one of the biggest player.
API Doc Ref. https://saferpay.github.io/sndbx/
Test Account Ref. https://test.saferpay.com/BO/Welcome
This like PostFinance ones, will extend of course use of Blesta not only on Swiss but all around Europe as for Blesta's concurrents SaferPay is already available by a long time.