There is also one more possibility.
When you guys flashed f30 bands, nothing was working.
Could be that’s ONLY because of md1img (modem firmware) incompatibility.
I’d try flashing just nvdata from the f30.
Even so, the md1img of the v3 F21 may have a filter, which in that case, would have to be edited, and not flashed from the f30.
I hope. I still have no real confidence that I have any idea about modem firmware. All guesswork (and Claude).
More like all Claude (and guesswork).
Checking into md1img “SPB whitelist”
SBP_DISABLE_BAND_BY_SIM_PLMN and SBP_DISABLE_LTE_BAND_BY_PLMN - these are the mechanisms that can disable bands based on SIM card’s PLMN
But that still shouldn’t matter…
Engineer mode doesn’t read nvdata band files directly.
It asks the MODEM via AT+EPBSE? (I think you can can run your own AT commands in diag mode?), and the MODEM decides what to report based on:
So even if nvdata has all the ER/EX band config files, if SBP says, “this SIM doesn’t support B66”, the modem won’t report B66 to engineer mode.
Download, to actually check support:
So, it’s possible I already did all that needs to be done. Or not… and I’m just talking Chinese (which night actually help in this situation).
This is just adding us bands not overwriting stock. Correct?
You mean the process I did?
I left md1img, nvram, and nvcfg alone.
I copied f30 parts to new f21 nvdata:
SS1A_011 - USA config
All the enabled US bands configs
I also removed corporate sim lock
So modified stock nvdata, NOT f30 nvdata
Though I wonder if just flashing f30 nvdata would be enough without the rest. Eitherway, if my process worked, there are many more bands enabled than the f30.
This is all assuming that I didn’t make mistake after mistake. It did make a call, and showed HD next to bars, so I definitely did “something”.
Interesting! Stock md1img v3 3.0.2 carrier support:
Filtered to US, there are alot more otherwise.
MAJOR CARRIERS:
310260 Tracfone / Total Wireless / Simple Mobile
310016 AT&T (Cricket Wireless)
310026 T-Mobile
310030 AT&T
310038 AT&T (formerly Alltel)
310120 T-Mobile (MetroPCS)
310140 AT&T (formerly Cingular)
310160 T-Mobile
310170 AT&T
310560 US Cellular
VERIZON NETWORK:
310004 Verizon
310005 Verizon
310080 Verizon (Straight Talk)
310200 Verizon (Cellular One)
310210 Verizon
310230 Verizon (Appalachian Wireless)
310310 Verizon (Illinois Valley Cellular)
310400 Verizon (CCWA)
310800 Verizon (Clear Talk)
310830 Verizon (Pinpoint Wireless)
310950 Verizon (Silver Star)
310980 Verizon (Big River)
311012 Verizon (Cellcom)
311220 Verizon (Rural Cellular)
311260 Verizon (Cellcom/Nex-Tech)
311480-311489 Verizon Regional (10 codes)
AT&T NETWORK:
310090 AT&T (Straight Talk)
310110 AT&T (formerly Centennial)
310150 AT&T (Affiliate)
310180 AT&T (formerly Dobson)
310220 AT&T (iWireless)
310240 AT&T (Plateau Wireless)
310250 AT&T (via nTelos)
310270 T-Mobile (GSM Alliance)
310280 AT&T (Cincinnati Bell)
310380 AT&T (Carolina West)
310410 AT&T (C Spire)
310490 AT&T (Syniverse)
310660 AT&T (Bluegrass Cellular)
310670 AT&T (Viaero)
311070 AT&T (New Cingular)
311090 AT&T (Aptos)
311170 AT&T (Pioneer)
311180 AT&T (Cross Wireless)
311221-311229 AT&T Regional (9 codes)
311390 AT&T (Cavalier/GCI)
311660 AT&T (Farmers Telephone)
311870 AT&T (Alaska Communications)
311880 AT&T (MTA)
311882 AT&T (Ace)
311940 AT&T (Illinois Valley)
T-MOBILE NETWORK:
310053 T-Mobile (Cellular South)
310054 T-Mobile
310070 LTE Discovery/Plateau
310470 T-Mobile (Open Mobile)
310680 T-Mobile (Cingular)
REGIONAL US CARRIERS:
310028 US Regional
310140 AT&T (formerly Cingular)
310560 US Cellular
312140 PC Telcom
312190 Colorado Valley
312240 AT&T (Five States)
312250 AT&T (Farmers)
312530 AT&T (Thumb)
312670 AT&T (West Carolina)
313100-313150 Guam/Territories (5 codes)
313390 Guam Telecom
313790 Alaska (Alaska Digitel)
316010 Bermuda (Digicel)
So, why aren’t the bands showing in engineer mode with my nvdata mod? Either my patch didn’t work, or there is more filtering.
Keeping an eye on this post interesting when I used to do this on Samsung phones using Odin all you had to do was flash the modem.img the hardware is the same. mtk chip in almost all qin f21 is myk6761 which is responsible for the Bands with that in mind everything is software related and can be reprogrammed if you know how. Only one of my orders in the past contained a different chip 8766b I believe but that’s long gone.
Hatzlacha
I used to do hardware unlocking for many years some chips needed a voltage change just to program them but that’s all they are microprocessor chips which now contain more sections to do more functions while keeping costs down for the manufacturer
Seems like the f30 modem is incompatible
i tried only replacing the md1img_a from the f30 and that didnt work
Course not
GitHub - AlikornSause/Notes-on-QIN-F21-PRO: My notes on the Duoqin F21 pro dumb/feature phone GitHub - AlikornSause/Notes-on-QIN-F21-PRO: My notes on the Duoqin F21 pro dumb/feature phone
Here’s a link to some good information on the Quin
Trying to look for more info on lwtg
As far as I know this does not have any info on new ones, even the 2nd revision.
Very recent
Anybody else with this phone willing to test?
I have this phone to test just not sure how to flash the files
Dumbdroid (The Operating System)
The Dumbdroid project is a custom OS built for these phones. While their website focuses on their own store, their GitHub and community discussions cover how to install their ROM on LWTG hardware for US use.
Where: shop.dumbdroid.eu or their GitHub under “Dumbdroid.”
Why it’s useful: They have recently updated their builds (late 2025) to better support newer variants of the Qin series. Their “December stable update” specifically addresses bugs in newer hardware.
What does dumbdroid have to do with anything?
It’s a system img that’s all
Also, AI has no idea what it’s taking about 
That never discussed these new phones besides for when I brought it up
You are right AI doesn’t know what it’s doing give me a few minutes I’ll flash the image on the stock firmware unless I need something else
You don’t need anything else, but you don’t have the modded nvdata
Dunno if that’s where the imei is stored but if yes, that’s the reason I took it off.
Give me an email or some way to send you a link.
