AT+CMUT=1 OR AT+CMUT=0 return ERROR

EG91,

AT+CMUT=?
+CMUT: (0,1)

AT+CMUT?
+CMUT: 0

AT+CMUT=1
ERROR

AT+CMUT=0
ERROR
Please help to check and clarify. Thanks.

Hi
What are the specific modules and firmware you are using? It is suspected that your firmware version is relatively old. Please provide your version and firmware so that I can give you the latest version

Thank you for your help.
This issue has been clarified. Mute setting is only working during the call. Can not preset it.

Hi Felix
We are using 2 version, Europe and NA
EG91EFBR06A07M4G
EG91NAFBR05A05M4G

Thanks.