[E173] Can't downgrade? v21 to v11

[george81]

Hello all, has anyone managed to downgrade from v21 to v11 for the E1732s-1?

I have one of the E173s-1 modems (CH1E173SM)

Device name: E173
Hardware Version: CH1E173SM
Firmware Version: 21 017 05 00 55
Software Version: 16 001 05 00 45

I only want to enable voice on it.. DC unlocker says it's not available on firmware But I have tried to downgrade to two different firmware versions, none of them worked:

E173Update_11 126 85 00 114_B427 exe
E173Update_11 126 85 00 209_B427 exe

After I enter my flashing password, the process "backup user data" starts, and then I get the error message "The wireless terminal inserted is not Firmware, update wizard can't work on "

However the dashboard was updated successfully (it had T-mobile branded before, now it has the generic dashboard)

Any ideas how I can downgrade my firmware so that I can enable voice on asterisk? I want to use it with chan_dongle

Hardware ver : CH1E173SM
Dashboard version : UTPS16 001 05 00 45_MAC15 001 08 01 45_LNX15 001 08 01 45
Voice feature : not supported in current firmware
SIM Lock status : unlocked
Wrong codes entered : 0 (unlock attempts left : 10)

Thanks again!

[flvby]

And nobody answered?