At least you wont be sleeping in it, and you have choice in a shared house whether to use the phone or a corded one. A big step forwards. Which models did you try?
http://www.wavegoodbye.info/Siemens_ECO_mode_DECT_phones.htmlCan you block TETRA? The lower frequencies such as AM FM seem to me to be very hard to stop. I have a Faraday lorry (100% dark) and it attenuates but not enough to stop all the radio signals. I make my own paint with graphite.
Do you get a significantly lower meter reading inside your FC from outside?
Have you tried it in the countryside?
Do you get significantly lower readings underground if you have tried?
I am trying to puzzle these things out.