I use Freedompop. Several people HATE HATE HATE them (like Suzy Ormon and FIRE).
Their tech support in nonexistent (literally, they do not have any tech support at the free level). Phone service is VOIP, and is pretty crappy under 4g. Texting is fine on 4G. Phone while on WiFi is just fine.
Why choose such a monstrosity? 200 phone minutes, 500 Texts, and 500MB of 4g data, for free, every month.
Some very important items to consider with them:
1. After purchase, you are enrolled in pay-services. If you do nothing, you will start to be charged. You must "Downgrade" the phone to get continually free service.
2. You MUST set up data overage purchases of $15.00 that automatically charge your credit card. You can NOT set it up that the phone just stops before using data for a fee. It forces your child to be data responsible. You can go into your account anytime and see usage, and there is a text just before the credit occurs, but there is a delay, so charges could happen before you know you are close to running out. Ask me how I know.
My 19 year old got her first phone when she was 16. That was when we discovered Freedompop and the free service. A year before that, she got a tablet that had 200Mb of free 3g through TMobile.
My 12 year old got one last year. She has had a few $15 charges(she paid us), and has lost use for some time. I would not pay for service for her(or me).
We use Alio, so no 500 text limit, but you still need to watch your data. 200 phone minutes is 199 more that we ever need.
If it stops being free, I will no longer have a cell phone, and will use my devices as WiFi only. My 12 year old daughter would lose hers. My 19 year old and wife would most likely buy a plan.
They have some nice sales on phones sometimes. My wife wants to upgrade. I am hoping to find an S5 for under $100 around Thanksgiving.