Verizon will not offer wifi calling any time soon. You CAN use this app above to make calls over data and wifi. Having a Google Voice number is also beneficial.
Verizon announced last fall that it will support wifi calling by "mid 2015"
However, there have been statements by executives since then that wifi calling is not a priority and Verizon "doesn't need wifi calling." So it is a bit bipolar right now in Verizon.
I do think Verizon will offer it, mostly because AT&T is also going to offer it.
My prediction - it will July or August, it will be called Advanced Calling 2.0 and it will include wifi calling and VoLTE/HD voice interoperability with at least one other carrier, likely AT&T.
One can only hope at this point. I for one think it foolish for any carrier to say that the feature is not of any use within their network. Unless a feature is going to cost a lot to offer rather than cost nothing to offer, even though it might put a small, negligible dent in data use, I agree that it should be an option to be looked at, at least in the nature of competition.
Although not surprising, anything a rep says about strategic corporate plans must be taken lightly. The reps don't find out what is going to happen until just before it is going to happen, not months ahead of time. Nor do they know corporate strategy.