First make sure that API mode is not enabled. This can be done by checking 'AP' parameter in XCTU. It should be of value AP=0x0 [Disabled].
Then move to 'Terminal' tab of XCTU or open any other similar tool like PuTTy or HyperTerminal and make active socket connection.
Once you are connected, enter keyword "+++" (without "") within one second duration. Make sure that there was period of 1 second silence before and after this keyword is entered. Once module enters command mode, it will respond back with "OK"