@will13am wrote:
I sense there is some sort of hardware or software problem with the phone that causes it to "disconnect" from the network. When a phone is not connected to the network and on standby, calls go straight to voice mail. I have never used iOS before, is there some sort of hibernation control on the phone that is putting it into too deep of sleep?
Apple provides exactly one setting for this: "Low Power Mode". It throttles down a whole lot of iPhone functions once battery charge hits <80% capacity - no user settings are provided to configure what gets activated or deactivated (or in what way, or by how much) when Low Power Mode engages, it's all or nothing. And other Apple softwares can (and do) automatically assert Low Power Mode, which functionally prevents it from remaining disabled.
It can be especially problematic on older devices. Older batteries (say 18-24 months old, having accumulated ~400+ full charge/discharge cycles) are usually chemically eroded enough that they cannot hold 80% of the charge they could when they were brand new (even though their embedded regulator chips falsely report "100% charge" to the phone software) - and they are designed to be "non-replaceable" - so in practice, Low Power Mode (along with all the crippling/throttling limitations it imposes on the iPhone) remains permanently active.
