You could tether the android to the iPhone so the android would get a Wi-Fi signal but there is no way to tether to piggyback off of the iPhone cellular network if you were wanting to say make calls from the android.
That said, you could tether so the android has Wi-Fi from the iPhone then get a free virtual number from Google Voice or other. You could then make Wi-Fi calls from the android using the google virtual number (semi anonymously)