Mobile developer needed

Job ID: 37350017

Budget: $30 – $250 USD

Requirements
1.when user receive incoming call, user can accpet it in phone1, but can't hear anything, only can hear through phone2.
2.If he wants to call someone(outcoming), user can dial number in phone1, but can't hear, only can hear via phone2.
Totally, phone 2 works as a bluetooth headerphone.
I am wondering if you have to build a app for phone2 , or 2 apps for phone1 and phone2.
the app will be worked between API 19 and API 24