proximity sensor on Sony Z3 Compact

[AC Question]

Does anyone know how to disable the proximity sensor on Sony Z3 Compact . My screen goes black as soon as I make a call, nothing I do will turn the screen back on. I have no dial pad, cant turn on speaker phone, have to wait for other party to hang up before screen will come back on. Seems like if I could disable the proximity sensor that may fix it, there is no option in setting for switch ON OFF similar Samsung, can you help me how to fix?