That depends on how fast your internet speeds are. If the internet connection speed at your house is less than 10 mbps for downloads or less than 5 mbps for uploads, a Network Extender probably won't be useful. If the internet connection is 10 mbps or more for downloads (also 5 mbps or more for uploads), and you have the money to spend on a Network Extender, then that will be your best bet if you do not want to have to use Wi-Fi Calling service.
We certainly want you to have the best possible service! There are always changes that impact our Network, some are controllable and others may not be. This can include cell site changes, foliage, construction, population changes, and interference. I am glad to know you are utilizing the option of Wi-Fi Calling. Do you have reception concerns outside of your home?