Only semi-related to this thread...
At our new home NE of Colorado Springs, out in unincorporated El Paso County, Verizon single is 1x in my neighborhood. Lots of dropped calls and low data signal. I called Verizon to see if they would give me a broadband Internet-based Cellular Extender. They told me I don't need it as our iPhone 6's have a "WiFi Calling" feature (Settings-Phone-WiFi Calling).
When that feature is on, so long as my phone's WiFi is connected to a broadband Internet service with decent bandwidth, my cellular calls can be routed to Verizon's network via the Internet. We just turned the feature on, on both phones yesterday, so time will tell whether it helps us - inside our home.
Of course, on the road, the feature is less useful unless you have access to a WiFi network that is well provisioned with Internet bandwidth. My fear is that we forget, leave the feature on and our phones connect to the WiFi we create in the coach with our own cellular router that uses Verizon. Then, I'm shifting my cellular voice calling from Verizon's cellular network directly, to their network via my data plan! I don't want to chew up my data allowance on cellular voice calls.