Turn Android phone into VOIP phone Data only?

I'm quite sick of paying $100 a month for a crap 2GB cellphone plan on Verizon, this is even with $10 off a month with my discount.  I've researched and it seems there are some people that have had success using a data only SIM card from a tablet in a phone and then using apps that make it a VOIP phone.  Does anyone know if this is a logical long term plan?  I would love to be able to just use my Google Voice number.  Would a cellular carrier be able to tell that my device was not a tablet and stop me from doing this?  I don't know a whole lot about these things and figured this was a good place to find someone that might.

Yes, Verizon is completely capable of determining what device is using the SIM card. As soon as your phone were to connect and register it's IMEI, Verizon would either disable the plan, or change it to a cellular data plan.

I'm unsure where you live Silver but I have a plan with Republic Wireless and it only costs 25/m for unlimited talk, text, and data. Sadly you're stuck with the Moto X, E, and something else but it's a pretty good plan. When you're at home it uses the wifi for calls/text/data. If you're looking to save money that might help you out.

Pretty sure your best bet would to be to get an unlocked phone and go on a prepaid plan most cost around $45 a month and you get unlimited call text and 3gb of data at 4g then you get knocked down to 2g trottled speeds if you exceed the cap. It sucks buying a half decent unlocked phone but if you can get your hand on a one+ invite its a pretty killer deal.

I've been strongly considering a One Plus with a prepaid plan however I have concerns about the cellular coverage.  At least in Verizons case I know they only allow prepaid customers to access towers that are owned by Verizon and not the ones that are leased.  However if I had the One Plus it would be on AT&T and I'm not sure if that same issue applies.

Most prepaid carriers run on at&t or tmobile (obviously there are a few exceptions) and yes you can bring any gsm unlocked phone onto something like net10 straight talk etc.  I have a nexus 4 running on net10 you just need to get the proper sim and activate online and you're good to go.

There are  about an equal number of prepaid virtual carriers on all major carriers, and I would argue that the majority actually run on Sprint. Such as Boost Mobile, Virgin Mobile, Straight Talk, Republic Wireless, Net 10, and Chit Chat, only to name a few of the more popular ones.

I don't know how exactly that works in the US and I'm actually pretty baffled by what you guys seem to be paying for your cellular services, but doesn't for example redphone do exactly what SilverS4sAreFaster describes here? It connects you through the data connection to someone else. I know this only works for encrypted calls when the other person is running the app as well, but it's basically the same concept. Not really convenient though.

That is possible, however the underlying issue is SilverS4sAreFaster would not be able to use a phone to do so. Phones are not allowed to have data only connections. They would have to use for say, a tablet.