If I plug this device and use it, can I still receive calls and talk or does it completely block the microphone?Updated a year ago

With this Mic-Lock, you would be able to hear the call but no one could hear you.
We call this function as SoundPass.

You can hear audio but mic security is always on. 
The output audio is a direct bypass so the audio quality is the same.

If you unplug the Mic-Lock then they will be able to hear you.

If you need to talk, simply hit speakerphone or unplug the Mic-Lock.
To restart the security, simply re-plug Mic-Lock.