I'm wondering if something like this exists because my father wants one for Christmas.

He wants to be able to dock or plug in his cell phone and have it ring through several cordless handsets throught the house. In a sense, he wants to be able to convert his cell phone to a home phone while at home.

I've tried to convince him that he should just keep his cell phone in his pocket even when at home, but he doesn't like that. And without a landline, it's sometimes tough to reach him when his cell phone is sitting in a drawer in the laundry room.

So, is there such thing as a home handset system like this?
He uses a Blackberry 9810, if that matters.

There are a number of these on the market and they work with the blackberry. Once you enter the house the phone transfers via Bluetooth to the house phone.