PMDG 737 & ATC COMMUNICATION

I have installed PMDG 737NG and my problem is that I can not find any buttons to start ATC communication on the main window screen.
At all other aircrafts there is a list of buttons among which the atc communication button is located. Now what?
Please help me locate the button if any or tell me how to have an atc communication with my new PMDG 737NG plane.
At all other aircrafts there is a list of buttons among which the atc communication button is located. Now what?
Please help me locate the button if any or tell me how to have an atc communication with my new PMDG 737NG plane.