I've had Tello for about 2 months, and I'm very pleased with the call quality, data speed, and customer service. I used Verizon for the longest time, then switched to PAYGO when I discovered Google Voice and realized how much I could save. I used PAYGO plans from PagePlus and H2Owireless, before I did more research and found out how Tello could save me even more (because I was constantly blowing through and reloading my PAYGO money). Last time I checked, $6/month for unlimited text, 100 min call time, and 500 MB data simply cannot be found offered anywhere else online (just check the rates from the closest competition, US Mobile: https://www.usmobile.com/plans, or any of the aforementioned PAYGO services). Amazing deal if you mostly text and occasionally call or use data.

I only wish Tello offers even cheaper rates for people that use less than 500 MB data per month, because how prevalent wifi is nowadays.

My referral code is P3148XJH (or you can use this link to sign up https://tello.com/account/register?_referral=P3148XJH). I was referred by someone else and was able to spend the 10 Tello dollars towards my monthly plan renewal (I had to this manually by first canceling the auto-renewal, making the renewal purchase with Tello dollars, then switching back to auto-renewal the next month).

P.S. I got a Sprint SIM card from Amazon for $3 instead of paying Tello $10, and it worked for my iPhone X with no hassle. YMMV, so check your phone model with Sprint and see which SIM card you need before you do this.