Also on Fi - I use hangouts for everything. On desktop hangouts has my SMS and Fi phone number available for voice calls. On the run, hangouts is on my phone for SMS, and I can use my phone as normal for calling people. It's far and away the best experience I've had with a Google product outside of search/gmail. They really need to look at what the Fi folks are doing, because it is truly excellent.

I can do this and I don’t have project fi. I’ve got a google voice number from a long time ago, and I can text from that number via Hangouts in gmail or on mobile.

Yeah, same. Hell, as a kid, I'd use GVoice really often just to send texts when I had wifi but no cell signal, or had a device without cell service (like a tablet). Saved me a couple times when I was younger and, say, ran out of toilet paper.

I was a Fi user for about a year, but had major issues getting the phone to switch back to the cell network when I left my house. We live in a little valley with poor reception, so the phone seemed to "give up" on cell service, and then I'd have to reboot it after I left my house to get it to reconnect (wifi calling worked fine while I was home).

pushbullet (plus a few other apps) also recreate this functionality. Buggy and it's $5/month but I really use the hell out of it.