If you are on any carrier in the US and have an unlocked phone with a post paid account you can switch to Sprint for a free year of service until 11/30. Just enter your MEID and current phone number to test if you qualify. Get free forever, or until bankruptcy, like with RingPlus on FreedomPoP, which will be on Sprint or AT&T. Verizon doesn't discount much. If you don't have a phone Virgin Mobile is offering a $1 if you buy one, also unlimited for 6 months.* T-mobile gives free Netflix.
*Offer ends 9/30/17. Excludes taxes. Regular rate of $50/month applies after promotional service period. Only with AutoPay. iPhone is locked for a year to Virgin, if you unlock it it isn't welcome to work on Virgin anymore. If you buy your Inner Circle phone from Apple it isn't locked, but you can still get the $1/year offer.
PS my first bill arrived for $63.73, seems that in the porting issues somehow I have ended up on the paid plan, rather than free. I am assured that in 3-5 days all will be well :) Keep in mind that I brought my own phone and SIM and also seem to have violated the web onlyness of this offer.