While everyone on this board seems to be obsessed with how to obtain the cheapest GV alternative on their obihai devices (probably fair given it's an Obi board) and regurgitates the same questions and answers all the time, I thought I would bring something new to the conversation.
My journey took a different path and I discovered VOIP on mobile. Using mobile SIP clients (Acrobits Softphone/Groundwire or Bria) and some of the same voip providers, localphone, CC,
voip.ms etc. I can have GV forward to both my cell phone and obihai, allowing me to answer calls where ever I am - the true promise of GV. I can also spoof my outbound number with my cell phone number (or GV) allowing me to save on cell phone minutes, without the called party being any wiser.
I ended up learning a lot along the way - pro's and cons of the different mobile SIP apps, G.729 codec and the applicability of various codecs, TCP vs UDP and all the trade off's with battery life etc. It's been quite fascinating.