Any wireless bridge/adapter to connect the rj11 connector to the phone and Xfinity modem?

My Xfinity Modem is at a higher level in the equipment room. If I have to connect a telephone to the Xfinity modem, I will have to place the telephone's main base in the equipment base on that elevated rack. I was wondering if there is a wireless adapter/bridge that I can plug into the modem's rj11 connector and the wireless receiving end on the phone (if there is one).

I rather have the telephone's base in my Living room. I have the extra handsets in various bedrooms and other rooms, but the actual base I prefer to keep in the living room.

Is there such equipment available? please guide?