Usually 4 numbers you can choose freely.
- How do I implement the blutooth feature?
By pairing it with another BlueTooth device. Most bluetooh devices names are hidden so you get no weird connections going on.
1) Setup a pin code
2) Publish the name of your bluetooh device (Samsung phone or something) for about 60 seconds or so.
3) Go to the other bluetooh device
4) Pair it with the published name of the bluetooth device at 2)
5) Enter pin