Do you have good broadband? If so, there is a solution for you, especially on Verizon. You can purchase a 4G LTE Network Extender, which plugs into your router and is a true 4G mini cell tower right in your home. The network extender isn't one of the lame "repeaters" that tries to amplify far-away cell towers (which usually don't work). Nor is this a glorified router for terrible wifi calling. The Network Extender is true 4G LTE signal, which will give you full bars and excellent call quality, routing your LTE call through broadband and out to the network.
Further, the best thing you can do is turn wifi calling off, especially if you have this type of LTE network extender. Wifi calling generally is terrible. But 4G and LTE calling is usually pretty great. And I can confirm this particular device from Verizon is really excellent, full bars, crystal-clear call quality, no drops.
We have an old "free" 3G micro-cell from AT&T that we stopped using when we got WiFi calling, because we like how with WiFi calling we can make calls with our iPads or Macs even when our phones are either off, updating, or just unavailable.
Xfinity here is up to 983mbps max speed in our area, but I am at 439 mbps down/41 up right now. The problem with the old Micro-cell and/or WiFi calling now is when we leave the house and the call doesn't hand off to the cell towers consistently and we drop calls fairly often when that happens.
We have devices on AT&T and T-mobile and both are equally bad with barely 1 bar of LTE. haven't had Verizon since 2009 (get a 24% FAN discount through work with AT&T). I don't know if AT&T will offer a free LTE Micro-cell now, since we haven't had our old one plugged in for years once we got wifi calling.
Also, if we plug the old one back in, it only allows our 10 primary devices in "group 1" to connect, but not the 3 devices in group 2 (Apple Watch, iPad mini, and my mother-in-law's iPad when she visits). And, one of the 10 primary devices in group 1 is my brother who doesn't even live with us and can't use the Microcell, but needs access to international day pass which is only on devices in group 1.