47
External CODEC contains a side tone circuitry to do this. The side tone hardware is 
configured through the following PS Keys: 
  PSKEY_SIDE_TONE_ENABLE 
  PSKEY_SIDE_TONE_GAIN 
  PSKEY_SIDE_TONE_AFTER_ADC 
  PSKEY_SIDE_TONE_AFTER_DAC 
7.2.6.3 Integrated Digital Filter 
TBA