I'm using a SIM900 module to browse the Sim Tool Kit menu and perform some actions. I'm able to get the top level menu but can't go further. Below is my AT commands and responses:
AT*PSSTKI=1
OK
AT+CMGF=1
OK
AT*PSSTK="SETUP MENU",1,1
OK
*PSSTK: "END SESSION"
AT*PSSTK="GET ITEM LIST",8
*PSSTK: "GET ITEM LIST",1,128,4,"eZ Reload",33,0,0
OK
AT*PSSTK="MENU SELECTION",1
+CME ERROR: operation not allowed
I receive an "ERROR" when I send the command to select the menu item.
I'm using this SIMCOM official STK guide
Any help would really appreciated.