My wifes 4s arrived last night. I have a panasonic wireless phone
system at home that pairs with 2 usb devices. I don't have a land line.
It's great because I have phones upstairs and downstairs. If my phone
gets a call it rings all over the house and I can pick it up. Before, I
would miss the call if I didn't hear the cell phone ringing or couldn't
get to it in time.

Works fine with a variety of different phones we've tried, except the
4s. The 4s pairs to it just fine, transfers contacts to it. When a
call comes in, the Panasonic unit does not ring. The iphone does not
ring or vibrate either. This is bad because unless you are staring at
the phone when it comes in, you would not know. It works just fine
paired with a car bluetooth kit.

I've seen other similar problems on the web... it's frustrating.