Only worth getting an ATA if you already have a lot of DECT phones you want to reuse, or need it to support older equipment (alarm systems for example).
Personally I'd get a something as mentioned, a new DECT system that supports VoIP. Not only is it a tidier setup, you will likely save on power consumptions costs. The Yealink I have (W60P) only draws 1.2 Watts, the handsets once charged register 0 watts. This is quite a bit less than the analogue DECT base station I had a few years ago and will pay for itself given time.
Also with an ATA that outputs analogue it will lose you the ability to easily benefit form HD voice, especially if feeding into older telephones, and things like Caller ID may not work as expected.
Edited by E300 (Tue 10-Aug-21 09:27:25)