Program it onto a 168 or 328 based Arduino (Uno, Duemilanove or Diecimila - not a Mega or Leonardo). Connect headphones or an audio amplifier to digital pin 3. Note that currently, Talkie only on 168 ...

Arduino OPTA and Arduino OPTA DIGITAL shares an I2C bus and a sort of UART bus ( OPTA Tx is wired on all OPTA DIGITAL Rx). Arduino OPTA has a PIN that goes toward expansions (other Arduino Digital), ...