Bluetooth and Virtuoso on raspberry

Hi, I have Volumio “Virtuoso” 2.729, running on a RASPBERRY PI 2 B+ with HifiBerry DAC plus, and I can’t pair my Samsung A5 smartphone with bluetooth.
I have installed a “Trust” mini-bluetooth-usb-adapter on raspberry, and when I try to connect my phone with Volumio, i don’t know what pairing-code to insert.
I tried with 0000, 1234, 1111 but Volumio says always “not-correct”…

Can you help me?

Massimo

… sorry, but I would just like to know which PIN to put here, to connect a PC (or smartphone) via bluetooth to Volumio
Volumio bluetooth.jpg