Re: "Sprint, the US' fourth largest and rapidly failing telco"
I used to own a phone on the Sprint network. I have moved that number to AT&T.
Around here, Sprint was:
* the slowest network; three bars of LTE would be 4 Mb/s down, 2 Mb/s up. while three bars of T-Mobile was 20-30 Mb/s and three bars of AT&T right now is 25 Mb/s.
* the least reliable network; I had dropped calls all over, and multiple dead zones where I couldn't make calls because I had no connection. In multiple areas I could make calls, but the connection was so poor that one side or the other or both had problems understanding what was being said. This rarely happens with AT&T or T-Mobile. Note that for years I used Motorola and Samsung flip-phones on T-Mobile, and had a brief (not nearly brief enough) fling with Android also on T-Mobile, and had Samsung Windows phones on Verizon followed by iPhones on Sprint and AT&T. I'm pretty sure that the problems were not with the phone. (Except with the Android phone on T-Mobile. That was the phone, alright. I've never had so much trouble before or since. I've had no problems with the iPhone which replaced the Android.)
* the network with the worst customer service. They declined to admit that there were problems, even when the call they were on was breaking up due to a bad connection. They declined to admit that their network coverage was bad even when it was impossible to get better than two bars and there were dropped calls from inside their own stores. (That's stores. Plural. I demoed the problems at three stores locally, while showing that T-Mobile had no such problems.) They promised to call back and never did. They promised improvements in the network, notably new towers, which never happened. And they really, really, REALLY hate the though of an unlocked phone, possibly because such a phone would probably be headed to another cellco's network; it should be noted that my phones with AT&T and T-Mobille are both unlocked and were from the moment I got them, though admittedly AT&T tried hard to avoid that. Sprint customer service was actually worse than Verizon's, and I'd left Verizon for Sprint in large part because of Verizon's customer service.
AT&T and T-Mobile both have their problems, but they're both faster and more reliable than Sprint, though not as fast as Verizon. Their customer service is not quite as bad as Sprint's or Verizon's. I've had a number on T-Mobile for more than a decade now, during which time the other number has moved from Verizon to Sprint to AT&T. I've tried all four of the Big Four. T-Mobile and AT&T are the least objectionable. It is remotely (very remotely) possible that I might move a number to Verizon again. It is extremely unlikely that I will ever again do business with Sprint. Yes, they're that bad.