My fix is pretty simple actually, I just set my primary voicemail to Google voice, so that all my missed calls from either one goes to my google voice voicemail, this way when people call me Ill be able to get a notification through wifi instead of through data when i have no single.. I know its not the same as being able to receive calls but it notifies you when you have a call.
Next I just downloaded the vonage app which lets you make free calls to USA numbers and I think canada.. So after I get a voicemail notification, I just call the number back.
Feel Free to post your alternatives to wifi calling in this thread, i would love to see other ways users live with out it
Now this only works if they leave a voicemail. so dont expect google to just notify you every time you get a call.
This is just my simple fix for having no wifi calling.. i figure if they dont leave a voicemail.. then their call wasnt that important..