Thanks for doing the leg work on this one! My earlier attempts to find a solution were frustrating and fruitless.
I had the same problem with my Galaxy S7 using Verizon and the solution found for your Edge put me on the track to fix it so I can now do calling over wifi with my phone! The key was finding 'Access Point Names'.
On my phone, I went to Settings, Connections, Mobile Networks, Access Point Names. The only one listed there was Verizon Internet [VZWINTERNET] and it wasn't selected, so I touched the circle to select it. It worked! When connected to our home wifi network calls go through faster and the sound is crystal clear...we live in the country and are on the fringe of a cell so the signal is weak and we have problems with dropped calls and voice fading in and out.
We use Charter Spectrum Cable for our internet service.
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