We actually have not unreasonable coverage at our house. But because the walls are made of stucco (and at least partially because I am sort of a gadget-head), I went ahead and bought a Network Extender. After using it for a little while, my wife, who is home much more frequently than I am, reports that she often has a problem where the other party cannot hear her and she must call back.
She has this more frequently on her iPhone 4S than she does on our house phone (which is a Home Phone Connect box).
I'm sort of an expert at TCP/IP networking. Our Internet connection is Comcast 50/10 service, and every speed and quality test I run comes back stellar. Normally, I'd think that the remote party having problems hearing would be an uplink congestion issue, but I find that sort of hard to believe for our connection.
I've left the Network Connect unplugged today and will get a report back from my wife when I get home as to how her phone day went. If it was no better, then I can conclude that somehow she got a dud phone, I think.