I have an Interphone F4MC on my motorcycle helmet and with my iPhone ( which has now been amazingly replaced ) i used to bluetooth sync to my helmet and be able to press down on the F4MC it would load up siri automatically and i could say " ring fairphone " and then Siri would ring the contact fairphone. Now it pairs fine to my Fairphone and everything works perfect apart from the voice dialing when i press ’ down ’ on the F4MC nothing happens does the fairphone not support this type of feature? Please say yes and tell me i need to do something real easy 
I would suggest that this is a special Google feature which could be achieved through Google Now or so. I don’t have any experience with this though. Maybe you should look around on the help section of your headset’s website.
I recently installed Google Now Launcher and when the phone is wake and unlocked I can say “OK Google” and it will await my next command which could be to call a number “Call XXXX”. I guess if you get the F4MC to wake the phone the call command can be made.