Sorry to resurface an old thread, but I thought this might be useful to some people.
tl;dr I9100T phones seem to need I9100T modem firmware to ensure usable data speeds. They can be flashed with ordinary I9100 ROM and kernels, but reflash with I9100T modem firmware afterwards.
I think there is more of a difference between the I9100T and the standard I9100 than just the SARS value. Here is why I think so.
I have a I9100T purchased from Telstra in Australia - and I use it on the Optus network. When I received the phone it had modem firmware DVKF2 and kernel DVKF4.
The first thing I did after getting the phone was to flash it to Cognition v1.31 (XXKG3). After a few days I realised I was getting terrible 3G speeds – like 900ms pings and 30kbps up/down. So I flashed the modem to DUKF2 (I couldn’t find a DVKF2). Things seemed to perform much better but my phone seemed to jump from 3G to H intermittently and while speeds were fast, there was large “gaps” as it re-negotiated from 3G to H and vise versa.
So with the DUKF2 modem firmware in place I went searching for solutions and found the *#301279# code (which lets me control 3G, H and H+ modes). Just to repeat, I am using the Optus network, so there is no possibility of me reaching H+ speeds. My results are from the SpeedTest app. Here is what I found:
- 3G only: Speeds were only marginally better than flashing the modem with a non-I9100T firmware. 250ms pings 300kbps down / 200kbps up.
- 3G and H: The odd part is that in this mode the phone never jumped up to H. It stayed on 3G all the time. Weird. Anyway, I was getting 180ms pings and around 2 Mbps down / 300 kbps down. Now, things seemed to be more stable. After the initial ramp-up in speed, the chart would roughly resemble a table top as if I was hitting a speed limit.
- 3G, H and H+: This enabled the switching up to H mode. The speeds were the best here as I could get anywhere between 2-4 Mbps down and 300-500 kbps up. Pings around 100-200ms. The problem was the speed was “erratic” The charts were nowhere near as consistent as being in 3G and H mode (where only 3G was operating). This is because the phone seemed to negotiate between 3G and H and that would cause gaps. Sometimes it did this 2-3 times in the one test – and the test only goes for something like 10-15 seconds!
Just to make it clear, I tried all of these modes under a few different modem firmwares such as XXKF2/3 and XXKG3 that were made for the I9100 and I had terrible speeds regardless. It was not until I flashed I9100T modem firmwares did the speed improve.
What do you guys think? I have read that others in similar situations (Telstra phone I9100T on Voda or Optus networks having poor speeds). Or could it just be my phone and I should return it?
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