Microphone not working for JBL wireless headphones on macbook air- OS mojave

I am trying to use new JBL Elite 300 wireless headphones on new macbook air with a calling software, called 'close' for dialling numbers.

The bluetooth is connected and I have paired and selected the headphones and the person answering can not hear me.

I have selected the headphones in sound preferences and audio midi setup and on the software program. Any help would be appreciated.