Background
1) We currently have ADSL.
2) The house has minimal data cabling

3) The phone wiring in the house (5 years old) is not star wired

4) In the future we may switch to UFB.
I'm planning to: -
A) Buy an ATA that will plug into a port on the wireless router (NetGear WNDR_3700).
B) Run a phone line from one socket direct to the ATA.
C) Plug one of our existing DECT phones into this socket.
D) The other 2 DECT phones can connect to this one via DECT (works now).
E) It would be a bonus if we can also have an SIP app to install on our smart phones - 1 x iOS 1 x Android.
Will this work with ADSL? Will it keep working if we switch to UFB?