Voice recognition services even on dedicated products like those from Amazon and Google are handing off the heavy lifting of the actual recognition to an external service, so assuming an app is doing the same, I don't see why not.
Which service specifically are you referring to.
Text to Voice I expect to at least be supported by standard by Android in some form, but the other way around ?
First I have heard of it, at least on a mobile device.
Calling a contact by voice is most likely simply comparison of a stored recording, something very different.