Need Help With Remote Access From 1 Android Device to 3 Android Devices..

Hi everyone

I am finally getting around to tackling an issue that I have been putting on the backburner for too long. I need advice on the simplest way to set up 3 android devices (all sony xperias) to "call" ,notify or just connect to a master android device that is my main device. All 3 will be "slaves" and the master needs to connect to them , control the display and then I terminate the connection manually from the master .

Basically i create and test apps on different devices (all Sony Xperias) and need to notify or call the master device in a simple way that all devices can use. I feel a little out of my league with this so thought I would ask for help as its frying my brain and I cant work it out.

Thanks in advance guys