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

Send: AT

Receive: AT
Receive: 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, the modem will answer OK.

For modern modems command is:

AT^SETPORT="FF; 1"

If it is successful, the modem will answer OK.

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

The way for a more modern Huawei E3372h is here: