The ISD-300 is a fixed-function device and cannot be programmed. Default configuration information is contained in internal ROM contents, but an external I2C EEPROM can be used to store custom configuration data. Please see page 7 of the ISD-300 datasheet for more details.
Please note that the ISD-300 is obsolete and the functional replacement is AT2LP. All the related collaterals of AT2LP can be found in the link here