(for Eclipse insiders only)
You know who you are: You inhabit inside units that are protected from many things, including cellphone reception. Here's the solution that works well for me. I have been using a Samsung-Verizon Network Extender. It improves my Verizon Wireless service from being spotty to being perfect. It needs to be hardwired to your internet router by a RJ45 cable.
The newest model seems to be the 4G LTE Network Extender 2. They claim that this works with all 4G devices, hopefully meaning: All 4G cell phones no matter what network they are on, whether Verizon Wireless or not. If you complain to Verizon Wireless about your rotten coverage, they might give you one for free, otherwise it's $250. Amazon might have a refurbished 3G model for $70 which might work as well.
Depending on your phone and your service provider, it might be possible to enable only Wi-Fi calling which should force your calls to go through your Wi-Fi router instead of a cell tower. This solution is free!
Before you spring for the $250, check all this out for yourself. This is merely a tip to help you get started.