Check  your 3G / 4G modem. If it is in stick mode then use the Huawei terminal to transfer modem into modem mode by a AT ^ SETPORT = "FF; 1" or the command AT ^ U2DIAG = 0. Modem in HiLink mode does not respond to AT commands, no modem can be found , no SMS can be sent.

Disabling HiLink mode and transfer of 3/4G-modem to mode "modem only".

The very first thing to do -  to disable  a request / check the pin code in the modem software. After that you need to get a SIM card from the modem and all subsequent actions be made without a SIM card.

• To disable Hilink mode in old Huawei modems, for example in E3232, connect the modem into USB-port and go to the browser at http://192.168.1.1/html/switchProjectMode.html
  The modem restarts and in a Device Manager You can see two serial interfaces  
• May be will need Huawei Modem Driver
• Switch to "modem only" - run the program Huawei Modem Terminal. Later in the program, select your device from the top «HUAWEI Mobile Connect - 3G PC UI Interface» and push Connect. Then need to check whether modem is responsible . In the bottom string write command AT and push Enter. You should see something like:

Send: AT

Recieve: AT
Recieve: OK

  If so , the modem is responsible, and we can give him commands. Switch it to the "modem only" state by command:

 AT^U2DIAG=0

If it is successful, modem will answer OK.

For modern modems command is:

 AT^SETPORT="FF; 1"

If it is successful, modem will answer OK.

To change HILink mode into modem mode, it is necessary to change driver, sometimes You can use Huawei modem driver, or may be E3372s modem drivers.

Way for more modern Huawei E3372h is here:

• Visit either one of these sites to calculate device specific "Flash code" based on your IMEI and write it down.
• Online calculator 1
• Online calculator 2
• Download and extract this ZIP that contains required tools, drivers and firmware images
• Install "[1] Mobile Broadband HL Service" by running mbbServiceSetup.exe
• Installs RNDIS driver
• Installs service to switch from CD emulation to RNDIS (like usb-modeswitch on Linux)
• Install "[2] Datacard Driver" by running DriverSetup.exe
• Installs serial port drivers (v5.05.01.00)
• Insert E3372h-153 with HiLink firmware to USB port
• Preferrably directly to PC, avoid cheap chinese USB extension cables.
• Open Device Manager and verify that RNDIS interface is present under Network adapters
• Open command prompt and "PING 192.168.8.1" to make sure HiLink firmware is running
• Run "sw_project_mode.cmd" from "[3] Switchmode E3372h" folder
• This will enable "PC UI" serial port required for firmware upgade
• Wait until you can see it under Ports in Device Manager
• Run "Update_WEBUI__Hilink_V7R2_9x25_CPIO.exe" from "[4] Huawei E3372h WebUI"
• This updates user interface but doesn't touch rest of the firmware.
• If you have Error Code 13 this will fix it. Code 13 ("Authentication failed") is caused by failed attempt to flash firmware resulting in Error Code 19 ("Download failed").
• See HUAWEI_Module_Firmware_Upgrade_Guide_on_Windows_V100R001_01(5).pdf for complete list of error codes.
• Wait until WebUI update is complete and you can ping 192.168.8.1 again.
• Run "sw_project_mode.cmd" from "[3] Switchmode E3372h" folder
• Run "E3372h-153_Update_.exe" from "[5] Huawei E3372h-153 HiLink FW" folder.
• This upgrades (or downgrades) your HiLink firmware version. You will need Flash code from one of those calculators to do this.
• Wait until HiLink update is complete and you can ping 192.168.8.1 again.
• Run "sw_project_mode.cmd" from "[3] Switchmode E3372h" folder
• Run "E3372h-153_Update_.exe" from "[6] Huawei_E3372h-153 Stick FW" folder.
• This finally changes firmware from HiLink to Stick. You will need Flash code again.
• Wait until Stick update is complete. You can no longer ping 192.168.8.1 and RNDIS adapter has changed to "HUAWEI Mobile Connect - Network Card".
• Run "putty.exe" from "[7] Putty" folder
• Find serial port name from Device Manager, for example in case of "HUAWEI Mobile Connect - PC UI Interface (COM15)" port name is COM15
• Click Serial on right hand side of Putty screen and type COM15 or whatever your port is.
• Click Open on botton of Putty
• Type ' ATE1 ' without quotes, you won't see what you type and DO NOT try to use backspace. If you did it right you got ' OK ' as reply. Ignore ^RSSI etc. lines you might also see.
• Type following commands one per line to see info about your device and verify connection works. 
• ' ATI '
• ' AT^FHVER '
• ' AT^VERSION? '
• Get current SETPORT value by typing ' AT^SETPORT? '. You might want to write these down if you ever want to revert back to defaults. Mine was ' ^SETPORT:A1,A2;12,1,16,A1,A2 '.
• Set new SETPORT value by typing ' AT^SETPORT="FF;12,16" ', this disables CD emulation, disables modem emulation (PPP) and enables NCM mode.
• If you want to keep PPP support for example for older router with USB port use ' AT^SETPORT="FF;12,10,16" ' instead. Remember that you won't get full speed with PPP.
• Reset modem by typing ' AT^RESET '.
• Close Putty now.
• Done.