I am using an iPhone with the SIM Card removed. The good side of this is it takes care of the security issues with SS7. The downside is you have to place a SIM Card on every update. It also nags you every time you power back up telling you there is no SIM Card (twice).
I am using a Hotspot from Tracfone, 1 gig for $15.00 per month. At the moment I have no idea how much talk or text I can get with 1 gigabyte. But I will update you right here as soon as I figure that out. My TracFone Hotspot uses Verizon’s Network.
I got my VoIP number from TextNow. Text and Talk are free but supported by advertising, you can also pay for the service to get Ad free Service. There are several VoIP service providers out there and I have no way of rating all of them.
The downside of using WiFi for your cellular service is Apple seems to disconnect from WiFi after the iPhone goes to sleep now. This is also good because the iPhone is no longer broadcasting the WiFi connections that it has connected to in the past. At the moment you may have to wake your device up every now and again. When I set TextNow up I was warned that 911 would not work. I think they mean the location services that normally work with 911 will not work. I hope iOS 10 takes care of that.
I am looking forward to iOS 10. I believe this way of using my iPhone will be even better.
You could use this idea on your iPad or iPod Touch as well. Yes you could use your iPad just like an iPhone. Although it may not fit your ear as well. LOL.
P.S. I use my home WiFi and when out and about use other secured WiFi to keep my useage in check.
Roy Frost from TheGoodAppleClub