This is a sub report from phase 4 of Norges Bank’s central bank digital currency (CBDC) project. The project began in 2016. Reports from former phases are available on Norges Bank's websites. Norges Bank has not decided on whether to introduce a CBDC, nor on the type of technology and design. In Phase 4 of Norges Bank's CBDC project, the work relating to the validation of technical solutions was supplemented by experimental testing. This work was carried out by a Validation Group (VG).1 This report discusses the experimental technology testing.