DECT 6.0 cordless phones work great when connected to an analoge interface. This is afterall, what it is designed to do and where it is used most. In a typical PSTN call, there can and will be multiple A/D & D/A conversions.
There will be a minimum of two, one at each end. Any more than two are added by the use of a digital cordless phone with a RJ11 analog interface.
Completely under user control.