Hey! I ported my number to Google Voice and I've been using it for the last 2 months or so and I love it! I keep my phone on silent pretty much all the time, so I miss the majority of calls that I get (they are 95% spam calls, which is why I keep it on silent), but it does ring through just like normal. I have the Google Voice app on my phone, I don't know if that's available for iPhones, but it's definitely in the Play store for Androids. I can't remember if I've used Voice while I've been out and about and off of my wi-fi, but I'm pretty sure I've used it with data as well.
I love it! I'm so glad I did it this way. I can still text people just like I used to and neither party is getting boned on charges for international texting. I can call my family in the US and it rings through just like a normal call. Flipping fantastic; highly recommend!