At this time there is no way to decode P25 Phase 2 under Windows (unless you have a Linux virtual machine of some kind running OP25, of course). The hope is that P25 Phase 2 support can or will be added to DSD at some point (for Linux and Windows) as well as (seriously hoping here) DSD+ too on the Windows platform.
Still not that much happening in my area with Phase 2 content but, that will change as time passes so, considering I can't afford a Phase 2 capable scanner then it remains to be seen if a software method (on Windows, obviously) will come along at some point.