Wesley's Tool-Box

As I mentioned in the previous VoLTE post, all three major mobile carriers in Korea have been supporting VoLTE for quite some time now. One glaring problem, though, is that cross-carrier VoLTE still hasn't been realized, despite years of negotiations. This seem to have introduced some confusion. The truth is that a device can always request a VoLTE call, but it's up to the network to decide to go with it, and if so, fully or just on the surface.

In the case of LGU+, the carrier's aging "2G" CDMA network had been a weak point, so it worked hard to have everything done on LTE, even voice. That's why it'll accept a phone that can do VoLTE even if it doesn't support the needed CDMA frequency band - namely, the iPhone 6 series. ( One caveat is that they are not accepted for registration on the network yet until official Korean debut. This is largely a decision of policy, not technicality. ) If you have such a phone, all calls will be connected as VoLTE no matter what.

But in case of SK Telecom (SKT) or KT, their "3G" WCDMA networks are still widely used. So they don't have the urge to go fully LTE. A call could still be made on either 3G or LTE, depending on the situation. No handsets on these networks get to make all of its calls on VoLTE.

Since I'm on SKT, I made calls to various phone numbers on my VoLTE phone, iPhone 6 Plus, to see how they end up connecting, and what quality they were.

Case	Caller 1	Caller 2	Connect 1	Connect 2	Quality
1	SKT VoLTE	SKT VoLTE	LTE	LTE	HD Voice
2	SKT VoLTE	SKT 3G (AMR-WB)	LTE	3G	HD Voice
3	SKT VoLTE	SKT 2G/3G	LTE	2G/3G	Normal
4	SKT VoLTE	KT / LGU+ VoLTE	LTE	LTE	Normal
5	SKT VoLTE	KT / LGU+ 2G/3G	LTE	2G/3G	Normal
6	SKT VoLTE	Landline (02 ~ 064)	LTE	Landline	Normal
7	SKT VoLTE	Toll Free (080)	LTE	Landline	Normal
8	SKT VoLTE	Special (15xx, 3-digit)	3G	Landline	Normal
9	SKT VoLTE	VoIP (070)	3G	Internet	Normal

As of this writing, two types of phones on the SKT network, the VoLTE-enabled phones (case 1) and the AMR-WB supported phones without VoLTE (case 2), can make end-to-end HD Voice-quality calls to and from iPhone 6 Plus. AMR-WB codec is the same codec used by VoLTE, but some phones support this only on 3G at a lower bitrate, e.g. iPhone 5 and Xperia Ray.

As mentioned earlier, cross-carrier VoLTE agreements are not yet in place, so calling VoLTE phones on other networks (case 4) ends up degrading quality. I'm hoping this clears up soon because there's no technical reason to be like this.

Meanwhile, most calls connect via LTE, with the exception of special numbers such as the three-digit numbers (including emergency) and the 15xx, 16xx numbers that companies use (case 8), as well as the VoIP numbers with the 070 area code (case 9). I understand that these numbers don't connect with high-quality codecs so LTE connection isn't necessary, but it doesn't explain why regular landline connections do connect via LTE.

Last year, iPhone 5S came with a motion co-processor called M7 that can collect various sensor data relating to iPhone's motion. The most notable use for this was recording how many steps a user took while carrying the device. In other words, the device acted as a pedometer. This year, iPhone 6 series has updated the co-processor to M8 and added another sensor - a barometer. The Health app that comes with iOS 8 makes an immediate use of this. It records how many floors the user has climbed, adding another dimension of knowledge to the user's movement.


Apps that are updated to use the Healthkit in iOS 8, such as Argus, can read this stair climbing data. The notification widget from Argus is able to display the number of floors I moved up during the day if I'm using an iPhone 6 Plus. If I'm using an iPhone 5S, there's no such data available, so the widget simply doesn't mention it at all.

While I'm comparing the data from both devices, I should note is that the pedometer function acted very similarly between each other. However, as you can see in the pictures, iPhone 5S consistently recorded a bit more steps than iPhone 6 Plus, for some reason. Perhaps the bigger form factor and weight of the 6 Plus dampened the recorded movement a bit.

Earlier, I've looked at how iPhone 6 Plus improved upon the image quality of the iPhone 5S. But it's not just the end result that's gotten better, but the process to get there, as well. Apple takes the whole photographing experience very seriously. One of the major improvements come in the form of the so-called "Focus Pixels", a marketing term for phase detection autofocus.

Traditionally, casual cameras employed contrast detection, which tries to pick out where the highest contrast difference between the pixels happens. Meanwhile, film cameras & DSLRs used the phase detection, which has the light from the subject split into two and tries to find where they become in-phase. The latter works well with continuous autofocusing, as well as in darker environments where contrast is less distinct.


In practice, the Focus Pixels provides the much-needed speed and accuracy improvements to the iPhone's autofocus. As you can see in the picture and the video above, iPhone 6 Plus locks onto the foreground subject's focus very fast and continuously. In contrast (no pun intended), iPhone 5S often does not respond to the movements of the foreground object.

When the iPhone 5S does detect the changes, the camera needs to move the focus back and forth, taking more time to find the right focus. In my experience with all the iPhones up to 5S, this occasionally results in focusing onto a wrong subject, even when I specifically selected the subject on the touch screen. This annoyance is no more on the iPhone 6 Plus.

What this means is that I'm now far less likely to have an out-of-focus snapshot even in a hurry. And I don't have to tell the iPhone to focus on something as often. A true "point and shoot", if you will.

It's already well known that iPhone's camera's quality usually ranks among the best in smartphones. iPhone 5S was no exception, so I wanted to see how iPhone 6 Plus could improve upon that. Naturally, I did a side-by-side photo shoot with the two phones for a few days and this is the result. All the photos here are cropped from the original resolution.

In the daytime shootings, the two performs more or less similarly at a casual glance. As you can see above, the details of the photos are very good and nearly identical to each other. I think it's a testament to how good the iPhone 5S already was.


That is not to say that iPhone 6 Plus hadn't had any improvements to introduce. As you can see in this photo, the details of the leaves receiving the sunshine are preserved better with the iPhone 6 Plus. Result from iPhone 5S looks more washed out despite having a slightly faster shutter speed. This shows that the dynamic range of the sensor has been enhanced. This is a good news if you don't want the somewhat unnatural look the HDR mode produces.

iPhones and iPads have generally gotten big boost in speed with every new generation thanks to the enhancements in their processing units. But with iPhone 6 series, Apple decided to temper the pace. Instead of something like 2x boost, the CPU was to be up to 25% faster and GPU, 50%. This should just cover the boost in resolution, so I suppose Apple felt that the iPhone 5S was already fast enough in terms of user experience.

Indeed, with both iPhone 5S and 6 Plus running iOS 8.0 (and recently, 8.0.2), the general "feeling" of the speed was nearly the same, both mostly quick. It was just that iPhone 6 Plus happened to display the contents on a larger screen. Also, the amount of RAM staying at 1GB didn't have any noticeable impacts. On both phones, apps do run fine, although running RAM-heavy processes (notably Camera and Safari) tends to gracefully quit the other app in the background. The stopped app restarts quick enough when switched back.


To gauge some solid numbers, though, I did run through the usual batches of tests. All tests were run with iOS 8.0.2 and with same installed apps and settings.

First off, the boot time was measured. This is from when the screen turns on with the Apple logo to when the lock screen is loaded. iPhone 5S clocked in at 38.0 seconds, while iPhone 6 Plus was a bit faster at 30.6 seconds. The 5S got a bit slower than with iOS 7 installed.