Huawei e5573s-156 how to unlock?

[Jam Barett]

How to unlock to another company or simcard.

Found Applications port COM3

Found modem : E5573s-156
Model : Huawei E5573 (untested)
IMEI : here goes the IMEI.
Serial NR. : here goes the Serial.
Firmware : 21.317.01.00.625
Dashboard version : WEBUI_17.100.14.01.625_MRE5
Web UI version : WEBUI_17.100.14.01.625_MRE5
SIM Lock status : unlocked
Wrong codes entered : 0 (unlock attempts left : 10)

For unlock, may require firmware change, check tutorial or contact support

Please helpme!.

[Valdemaras]

If firmware version begins with 2x.3xx.<...> unlock not possible, no way to flash it either, no downgrade, no solution, no workaround.