TL;DR
Until data providers (both land line ISPs and cellular ISPs) actually take responsibility for upgrading our infrastructure instead of blaming us for the overhead issues and capping bandwidth and data use, VOIP will NOT be reliable. Especially in rural areas. So now the FCC has trapped them into demonstrating that their networks are shit.
I normally hate the FCC but if I could give some suit a high-five for this one, I would.
-I cut the cord a few years ago when Google Voice came around. Ever since Voice hit I've been using it as my front end and routing traffic to the most affordable, most hackle androids I can find.
In Q1, 2012 with LTE tablets dropping everywhere, I took the experiment a step further.
From April of 2012 to December of 2013 I utilized a tablet data connection and apps like Talkatone to capture my Google Voice traffic without an actual cellphone number to route the calls out to. Exclusively. The tablet I tested was on VZW's Denver LTE network. Up until September of 2012 there was a consistent and reliable 20-22mb down no matter where I was and my VoIP traffic was excellent. Then the iPhone 5 came out and single handedly raped VZW's networks in Denver's Capitol Hill and Lodo areas. Centennial, Cherry Creek, and Highlands Ranch also immediately went to shit. All of which are areas I consult in frequently. I still can't get better than an average of 7 down around here. Go to any of our burbs or more rural regions and it just gets worse and worse.
Since then it has never been the same. I ended up picking up another Virgin Mobile Android device (Samsung Galaxy Victory) and I route my business Google Voice calls to it. (We love multiple GV phone numbers.) I still let my personal calls and texts ring out over data because I generally don't need to answer them immediately and let them go to voicemail. The transcripts are usually good enough for me to not even need to bother listening. Although for some reason Google's transcribe likes to turn "Hey Aaron" into "Honey." Always has. Don't think they intend to fix it...heh.