AT&T's LTE network often flaps on and offline on many towers from what I've seen, regardless of whether you got an iPhone or Android. 1 minute you'll have bars,

AT&T's LTE network often flaps on and offline on many towers from what I've seen, regardless of whether you got an iPhone or Android. 1 minute you'll have bars, the next to you won't be able to call 911. Meanwhile, Verizon has only kind of figured out VoLTE (and still has inbound call delivery issues) and is the most heavily loaded, slowest network in the US. Most of these issues are area dependent, but there is a reason why AT&T held off for so long when offering their new internet air product for 5G home internet, and why Verizon is so hesitant to add network load with their home internet product, hence both of them being very selective of what address is qualify for this service.