You know those little $0.66 and $2.98 charges that add up to over ten bucks on your cellular bill with nebulous explanations like "regulatory fees?" Those go to the carrier not any government. They are just "nibbles" so they can advertise $40 a month "everything" plans and still send you a bill for $48.97 and not be accused of lying.
This is why I have my doubts about the FCC needing to approve something that has been available from other carriers for many years now. And if it really was the FCC behind this, wouldn't At&t be facing a huge fine right now for allowing thousands of beta testers access to wifi calling?
I remember waiting for years for Verizon to get the iPhone then making the jump to At&t. I was happy I did but at first my most frequently used iOS app was At&t's "mark the spot" for dropped calls. After about 6 months to a year, I didn't get as nearly as many dropped calls, until about a month ago. Now it is happening again so I decided to buy an unlocked iPhone 6s or 6s+ so I could go carrier shopping on my own terms. Only Apple insists I rent the phone rather than buy it and I must activate it with a carrier in order to leave the store with it. Really?

I'm sick and bleeping tired of needing one of these blood-sucking carriers sitting between me and the only company I have learned to trust for my communications needs: Apple.
BTW, to add my guess about how long we have to wait... A very long time. This feature has been available on Tmo for years now so At&t will assume we are willing to wait some more years. This is why we need a complete end to contracts so a truly competitive market can exist.