Well... Today, I thought I'd try something a bit different to normal...
Having heard that EE SIMs like to keep you on 3G/4G the longest, I thought I'd try setting the S4 to its default network mode (i.e. LTE/GSM auto) and see what happens. With poor network selection on my old Virgin SIM, would the S4 behave better on EE?
The answer... yes and no.
Went to Northampton earlier today, and the journey (approximately 20 miles) was interesting. I knew that the whole route was covered by 3G, though some areas were quite weak. (Don't know if CTIL would be any better, given the fact that they aren't usually the best in regards to 3G/4G, but that's an experiment for another time.)
On the way to Northampton, the S4 was reasonable in network selection. Between Wellingborough and the outskirts of Northampton, it did flick quite often between 3G and 4G, due to them both being quite weak in areas. Once, near Earls Barton, it dropped from 3% 3G to 60% 2G - I suppose this may have been for call reliability? I know that calls wouldn't work on a -111dBm 3G signal. After a few seconds, it picked 3G back up again, at 17% strength. The rest of the way, once I'd reached the outskirts of Northampton, was all 4G.
On the way back... slightly better. Stayed on 4G for longer, though at some points, 4G was quite weak (-120dBm). I assume that 3G was also weak there, so it hung on for 4G. It did drop to 3G, but when 3G was stronger. At no time on the return journey was I shunted down to GPRS/EDGE.
So it seemed like the EE SIM did make a difference, and that the S4 picked the network type much more "smartly" - i.e. based on the signal strengths of other network types. So, for example, if you have a weak 4G signal, but a strong 3G one, the S4 usually goes to 3G - and if both 4G and 3G are weak, then what the phone does depends on how weak 3G/4G is, and how strong 2G is.
There was a footnote to this, though... At my home location, my phone has always tended to go for 3G, as our local mast for 2G and 3G is only about 200m away. However, a semi-local mast has now gone 4G. Upstairs, in my bedroom (where my computer is located), I can get between 40% and 50% 4G signal - hence, the S4 is going for that instead of the 60% 3G signal. When I went downstairs though, it went from a weak (0 bar) 4G signal, to 4 bars of 2G?! Seriously, WHY? 3G is available downstairs at 2-3 bars strength (at least 25%, up to 42%). In the end, it did go to 3G, but that begs the question: why oh why oh why is this wacky phone jumping to 2G when 3G is available, and at quite a strong signal strength?!
Looks like I'm going to have to stick to WCDMA only mode until either (a) EE's 4G is fully rolled out, so then I can use LTE Only mode when streaming (or risk the default mode), (b) I can find a way to change the internal thresholds at when the phone goes to 2G (instead of 3G), (c) I can find a way of having a mode that allows 3G and 4G, but ignoring 2G, or (d) the S4 finally bites the bullet in about 3 years time, and I upgrade to a VoLTE phone <- in this situation, LTE Only mode will suffice.
Anyone have a clue why this S4 is doing this? Or, more to the point, does anyone have an idea on how to add/enable an "LTE/WCDMA" mode in this S4?