With "hcitool scan" I search for the MAC address of my device which should be paired. Then I browse its properties with "sdptool search SP 00:00:00:00:00:00" (replace 00:00:00:00:00:00 with the MAC address of the device which should be paired). While doing this the bluetooth-applet requests a user defined PIN for the device.
I found a way to bypass this problem:
With "hcitool scan" I search for the MAC address of my device which should be paired. Then I browse its properties with "sdptool search SP 00:00:00:00:00:00" (replace 00:00:00:00:00:00 with the MAC address of the device which should be paired). While doing this the bluetooth-applet requests a user defined PIN for the device.