S7 Edge Verizon with U firmware and (modded) LTE bands

[SoNic67]

I have an SM-G935V phone. I have flashed the "G935U" Nougat on it to get rid of the VZW bloatware. Eventually I even got the Oreo OTA update. U version. The LTE bands remained unchanged after flash and upgrade to the "V" ones.
Now, I am using it on a VZW MVNO, so LTE bands where OK for me. Because I am curious, I have added all the LTE bands that the U version would have using the Qualcomm software, as described here:
https://forum.xda-developers.com/galaxy-s5/general/how-to-add-rf-lte-frequency-bands-to-t2886059
The NV cell #06828 for my original V radio had the value 4190. That means LTE bands 2,3,4,5,7,13.
I have changed that cell value to 2062440470751. That means LTE bands 1,2,3,4,5,7,8,12,13,20,25,26,29,30,38,39,40,41 (like they are on the U hardware, plus band 13 that is not found on the U).
Didn't add B17 because presently it's just a subset of B12.

Well... when I have traveled in EU, band 20 didn't seem to work. But I admit I didn't do extensive testing.
Now, in US, I had the occasion to test an AT&T SIM. To my surprise, I found out that bands 12 and 30 seemed to have appeared, and I even had CA with band 2 (LTE+). So it seems that that worked... see the pics from service mode.
Band 2 with CA on 12, band 12 with CA on 2 and band 2 with CA on band 30.

 

[SoNic67]

I just received, on my SM-G935V hardware, the latest Oreo "U" update (G935UUES4CRG3). I have install it and... of course the LTE bands reverted to the "V" ones, like always.
I have changed them back to the more inclusive set like I did before, however I took a screenshoot of the original LTE band NV value - for whoever is interested. The number is 4190 and that translates into LTE bands 2,3,4,5,7,13. Most of the sites quote more bands for the G935V, but I guess nobody really took the time to actually verify that.
And no, as you can see, just flashing the "U" firmware over "V" won't add any of the missing bands. Those band settings are stored somewhere else, in the modem non-volatile memory.

 

[SoNic67]

Did more experimenting. Changing the SIM with another one triggers the re-flashing of the CSC with the new one. Well... surprise the AT&T SIM added the needed bands with CSC ATT.
Picture attached.
Putting back the Tracfone SIM, CSC code was re-flashed (TFN) and... NV was re-written with the 4190 one (LTE bands 2,3,4,5,7,13).
See attached the pic of the Service menu *#2263# from AT&T CSC listing the bands. I can't take screenshoots from the TFN one, because that SIM blocks the Service RIL menu.
So, modding the bands can be useless, because it gets re-written by the CSC settings at every SIM change.

 

[SoNic67]

I found out how to enable the Service Menu *#0011# on my Verizon SIM, in case that anyone is interested.
The dialer code for enabling is *#22745927 , followed by MSL "000000". If your phone is carrier locked, the MSL will be different.

 

[SoNic67]

I just came back from a visit to Spain, Vodafone SIM, and I saw LTE bands 3, 7 and 20 working on my S7Edge Verizon with the "U" firmware - I have used cellmapper to map the towers.
No modding was needed, maybe because those are also present in the underlying V hardware.

 

[DMon04]

Very nice write-up. I'll have to try that!

 

[Totti_Cuba]

I read that I can install the firmeware of sm-935U in my sm-935V, but when i enter in sammobile page ,there is a huge list of 935U firmeware, wich of those do i have to select to work fine in my phone