On all of the custom roms I have installed, WiFi tethering has been built in. I am not sure what the technical jargon is, but I mean that the tethering had no effect on my bill. I have unlimited data so I use a lot of data. I have recently flashed my HTC One M8 with ViperOne after many hours of reading. To my disappointment when I launched the HotSpot app I got a warning saying that I needed Verizons service to use it. This has never happened with previous roms on other devices. I looked at InsertCoin and Revolution HD and both seem to be set up the same as ViperOne in that I must use Verizon's service. Does the Cynogenmod rom also need this, it looked like no? Anyhow, I am looking for a rom that does not require the Verizon Hotspot service. I have also tried the WiFi Tether that has been mentioned in several threads, but it does not work for me. I have used 3rd party apps in the past and they never seem to work as smooth as the built in tethering. I am not trying to bash the current roms, each of them are light years beyond what a rom built by me would look like. This site and the outstanding Android devs on it are the reason I am not an iPhone user.