For this example [Oscar] is using an Arduino with a Bluetooth module as a test device. His sketch first shows what devices are available, then connects to the one you select from the list.

Android apps for Arduino Bluetooth Control. What are some of the best apps available? Zach Wendt and Jeremy S. Cook walk us through the stages of development, considering the advantages and ...

In Connecting to Intel® Edison from Android* with Bluetooth* LE (BLE) describes a way to access BT via Arduino code but additional BT shield/kit is required.

Bob has kindly provided all the details and code via GitHub to be able to create your very own Arduino smartphone -controlled electronic scoreboard, which can be seen in action in the videos below.