Poor reception and dropped calls-Microcell

[fetalsono]

My family is at their wits end. We all have iPhone 4's with bumpers or cases. The reception in our house is horrible and worse than with the 3GS phones. I have twice tried the ATT Microcell and while it improved the number of bars, the garbled speech was a problem. I tried everything with the microcell, rebooting, re-registering, moving the unit, etc

Is there any other way to improve reception?
Also, just a question about cell phone reception. Is cell phone reception and data coming over the same network. A number of us were talking about what would happen if Apple does make a Verizon phone and lots of people (current ATT and current Verizon users) make the switch. Will the data (internet) network be overwhelmed, or the voice network be overwhelmed, or both.

Thanks