The system is voice activated using an advanced digital signal processor to analyze the voice and also its level. To keep the conversation active, talk at a level like talking to someone 2m away in an open space. The moment you speak softly, the microphone cuts ifself off and the other party cannot hear you.
This is designed to minimize panting and unwanted surrounding sounds from being transmitted to the other person.
For better speech detection, wrap the mic on the strap closer to your chin near the buckle.
If you are hiking and holds the mic directly to your mouth, you will hear each other consistently as the Mic's proximity provides sufficient voice energy to keep it open.