Originally Posted by The Pook
where can you get "6GB for $10" ? Mint Mobile is by far the cheapest in my area that I found and it's $15/month for 3GB but it's an introductory offer that after 3 months goes up to $25.
Look for "tablet" or "smart XYZ device" SIM card data plans. These can be used in a phone but they sell data at cheaper rates and tell you that you can't use it in a phone but it works. Look at plans from MVNO's, they end up getting the data cheaper as the big three providers re-sell unused bandwidth.
3gb of data for VOIP will essentially let you make unlimited amounts of calls. I think I measured it and 1hr of talk time is like 12mb or something. Unless you are a streaming whore 3gb is more than enough for what I would consider mobile use, it's a flat rate, no e-911 fee since it's VOIP, etc.
Here is the thing though, they don't tell you about this or Google FI. You are making VOIP calls through LTE, so what's known as VOIP over LTE, this is much different than VoLTE (Voice over LTE) which carriers are supporting to enhance voice calls.
Sending or receiving VOIP calls through LTE works fine in a major city with massive LTE saturation or slightly outside of one if you are stationary but making VOIP over LTE calls while on the road traveling between states or major towns where you only have one cell tower and you are downgraded to 3G or 2G data, there will be way too much jitter and the call will be unbearable. A normal cell phone with any major carrier with a normal phone number doesn't have this issue as the call gets routed through old school radio telephony 2G systems if a data connection isn't available in an area. People don't seem to know that data and cell is actually two separate things, but with stuff like Google FI you are doing VOIP over LTE which means phone calls over data only, no data no ability to call. Now I imagine Google might have some sort of fall back for this/agreement with mobile carriers allowing you to use traditional cell networks just in case so people aren't left stranded but the core technology and the way they make money off this is that it's them providing you VOIP over LTE service, re-branding it and selling it to you as something else hugely marked up. My point is, if you are willing to do the leg work you can essentially do the same thing but even cheaper. Like $10-15 cheaper.