AT+CFSREN command is used to rename a file in the Simcom modules.
Try the below script in the AT Command Tester tool
//Script: at+cfsgfrs - Get the free size of file system
//The AT commands in this script are applicable for Simcom modules only
//Check SIMCOM Module AT Command documentation
//Get the support for the commands
Output of the above script in the AT Command Tester tool