You need to pair devices when powering up CK3x00 for the first time. Subsequently, all connections between your phone and CK3x00 are automatically established when both devices are within a few meters range of each other.
Procedure
From your phone, display the main menu, select the CONNECT icon, press OPTIONS.
Select OPEN, check that BLUETOOTH is ON, select the PAIRED DEVICES tab, press OPTIONS.
Select NEW PAIRED DEVICE, select MORE DEVICES (searching).
Press STOP, Select CK3x00 (waiting).
Enter 1234 as PASSCODE, press OK.
After the 'beep', accept connection request pressing YES.
Known issues with this phone: No particular problem noted to this date.