@zionlook: Check this out: Mikrotik LTE Change IMEI · GitHub
Query which mode
/interface lte at-chat lte1 input="AT*PROD?"
"output: *PROD: 0" = production mode
"output: *PROD: 1" = non-production mode
Disable LTE interface
/interface lte disable lte1
Enter non-production mode
/interface lte at-chat lte1 input="AT*PROD=1"
Power cycle LTE modem
/interface lte at-chat lte1 input="AT+reset"
Confirm still in non-production mode
/interface lte at-chat lte1 input="AT*PROD?"
"output: *PROD: 1"
Display old IMEI
/interface lte at-chat lte1 input="AT*MRD_IMEI=R"
Delete old IMEI
/interface lte at-chat lte1 input="AT*MRD_IMEI=D"
Set new IMEI
/interface lte at-chat lte1 input="AT*MRD_IMEI=W,0101,11JAN1970,NEW_IMEI_NUMBER"
Enter production mode
/interface lte at-chat lte1 input="AT*PROD=0"
Power cycle LTE modem
/interface lte at-chat lte1 input="AT+reset"
Confirm still in production mode
/interface lte at-chat lte1 input="AT*PROD?"
"output: *PROD: 0"
Display new IMEI
/interface lte at-chat lte1 input="AT*MRD_IMEI=R"
Enable LTE interface
/interface lte enable lte1