Battery Issues with 9.1 AT&T Wi-Fi Calling
Is anyone else having major issues with CPU thrashing/battery drain when attempting to use Wi-Fi calling on AT&T?
I've had nothing but issues with AT&T's Wi-Fi calling. When it was first released back on October 8, 2015, it was unusable for me - calls to certain people failed or only one party could hear the conversation on those calls. So after a few attempts testing, I gave up. With the release of 9.1, Wi-Fi calling worked properly and calls were handled well. I was happy to see Wi-Fi calling working, as my desk is in a low signal area and I was looking forward to better voice calls.
However, after upgrading to iOS 9.1 I noticed that my battery drained rapidly and my phone was often hot to the touch. I started documenting this drain and would often have a dead phone by 3PM. Over the weekends and in the evenings, my phone seemed normal. I didn't have any of these issues with my 6 while at my desk, so I began looking for the difference. I turned off LTE Voice and Wi-Fi calling and my battery life returned to normal. The next day I turned LTE Voice back on and there was no negative impact on the battery, so the issue seems to be Wi-Fi calling alone.
I wanted to find some way to quantify the effects of Wi-Fi calling on my phone, so I did some searching in the App Store and found an app (System Status - activity monitor, network info, battery charge & memory manager) that allows me to monitor CPU, Battery, Memory usage of my 6s. It shows that as soon as WiFi calling is triggered (turned on & activated by a poor cellular signal), my CPU usage jumps from the 5-10% range to a minimum of 50% and stays there as long as WiFi calling is active. I have confirmed that it is not the fact that WiFi Calling is switched on, but it must be active (Wi-Fi appears in the status area next to AT&T.) Moving to an area of good cellular signal drops the CPU usage as soon as the phone stops using the feature (even though it’s still enabled in the settings.)
Heres a link to a video that I shot showing the impact of WiFi Calling on my phone: https://youtu.be/iaYR6aKy96k You can see that the act of triggering WiFi Calling pegs the CPU at 50% and in the minute that the feature is active, the battery drops 2% from 89% to 87%. There is another thread that deals with carrier settings, but it's for a European carrier: https://discussions.apple.com/thread/7296648?tstart=0
Anyone else seeing anything like this with AT&T? Other US carriers?
iPhone 6s, iOS 9.1
