EC200UEU-AA QuecOpen – AT+CUSD returns +CME ERROR: 58

Hello,

I am developing a car tracker using EC200UEU-AA with QuecOpen.

My module firmware is:

Quectel
EC200U
Revision: EC200UEUAAR03A07M08_OCPU

I am trying to use USSD. The module is correctly registered on the network:

AT+CPIN?
+CPIN: READY

AT+CREG?
+CREG: 0,1

AT+CEREG?
+CEREG: 0,1

AT+QNWINFO
+QNWINFO: “FDD LTE”,“43211”,“LTE BAND 1”,425

However, even the CUSD test command fails:

AT+CUSD=?
+CME ERROR: 58

I also tried:

AT+CSCS=“IRA”
OK

AT+CSCS=“UCS2”
OK

AT+CUSD=1,“14011#”,15
+CME ERROR: 58

I am sending the command through the QuecOpen Virtual AT interface using ql_virt_at_write().

According to the EC200UEU documentation/forum information, AT+CUSD should be supported on EC200UEU OpenCPU.

Questions:

Is AT+CUSD supported in firmware EC200UEUAAR03A07M08_OCPU?
Why does AT+CUSD=? return +CME ERROR: 58?
Is there another/recommended EC200UEU OpenCPU firmware version that supports USSD?
If so, could you please provide the firmware version or download link?

Thank you.