Bad coverage

WiFi calling is not a great solution.  It works okay but not great for calls, however any SMS texts between iPhone and Android require a cellular connection so you will have to use an app to text those.  I have found many people are reluctant to add another app to their phones.  I am pretty much done with AT&T and looking for a different service provider.

@caleonard

I have never had a problem with wifi call and text, no matter what device it was.  Calling may require you force wifi calling if cell connection is good enough for interference.  You don't need another app.   

@caleonard I second what @lizdance40 said. I've been using WiFi-C for years and we have no issues calling/messaging to iPhones or Android phones. That being said, messages to Android devices do take a bit longer but they do go thru. No extra apps needed.

The cell phone signal on my iPhone X is consistently at 0-1 bars in my home office and I do not get texts from my friends and family with Android mobile phones unless I walk to where I can get a stronger cell signal.  I have WiFi calling enabled and often use that for phone calls but tend to avoid making calls at home unless I walk to the kitchen where I can get 1-2 bars of cell reception.  Unfortunately I can't use the kitchen as my home office because the rest of the family needs to be able to use it as a kitchen.  I suspect my problems are a combination of the iPhone X being a horrible phone and my cell signal reception being so low.  The other family members are iPhone 12, iPhone 11, and Samsung S8 users.  They get better cell reception than my iPhone X but none of them are happy with the cell phone reception and capability within the house, or on the streets around the house, or in the park across the street.  The AT&T maps says we get 5G service all over here, as does the AT&T rep I finally managed to contact once, but I think the map lies and cannot be trusted.  Of course my iPhone X doesn't actually have 5G capability so there is that.  I am completely disgusted with AT&T and their cell phone service, as well as being disgusted with my iPhone X and Apple in general.  I am just trapped and paying off two of the phones on our AT&T account.  Right now I really HATE AT&T and Apple; neither company is interested in helping me find a solution.

WiFi-C is dependent on how good your WiFi connection is. We've had iPhones for as long as they've been capable of WiFi-C and they have always worked as expected. Sending/receiving from our Android friends has not been an issue either.

If your phone is setup correctly for WiFi-C, and your WiFi is reliable, then there shouldn't be an issue. If reception outside of your home is spotty as well then you are probably in a shadow or fringe area for reception and there is not much that can be done about that because it's tower related. Coverage maps are misleading in that they indicate where signal is available, not necessarily the quality or reliability of the signal. That is true for all carriers.