I know what you are talking about and no At&t does not provide this service like tmobile does. I forgot where I read it but the article stated that by offering WiFi calling, Tmobile is basically conceeding that their network is not the best and it has flaws in coverage. AT&T does not want to admit that flaw in their coverage. On the other hand I wish At&t had this option as seamless as Tmobile does for buildings that have spotty At&t coverage.
Edit: At&t is starting to offer this feature for some business phones, might only be iPhone. I believe it cost extra too, but not currently on the note 3.
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