kernel just after cable is connected:
usb 1-1: new full speed USB device using uhci_hcd and address 6
usb 1-1: new device found, idVendor=10b5, idProduct=ac70
usb 1-1: new device strings: Mfr=1, Product=2, SerialNumber=0
usb 1-1: Product: USB-Serial Controller C
usb 1-1: Manufacturer: Prolific Technology Inc.
usb 1-1: configuration #1 chosen from 1 choice
pl2303 1-1:1.0: cp2101 converter detected
usb 1-1: reset full speed USB device using uhci_hcd and address 6
usb 1-1: cp2101 converter now attached to ttyUSB0


invoking gnokii --identify:
krzychu@crusader:~> gnokii --identify
GNOKII Version 0.6.14
LOG: debug mask is 0x1
Config read from file /etc/gnokiirc.
phone instance config:
model: 6510
port_device: /dev/ttyUSB0
connection_type: 2
init_length: 0
serial_baudrate: 19200
serial_write_usleep: -1
hardware_handshake: 0
require_dcd: 0
smsc_timeout: 100
connect_script:
disconnect_script:
rfcomm_cn: 1
sm_retry: off
Connecting
Serial device: opening device /dev/ttyUSB0
Gnokii serial_open: open: Protocol error
Couldn't open FBUS device: Protocol error
Error in link initialisation: 1
Serial device: opening device /dev/ttyUSB0
Gnokii serial_open: open: Protocol error
Couldn't open FBUS device: Protocol error
Error in link initialisation: 1
Error in link initialisation: 1
Telephone interface init failed: Command failed.
Quitting.
Cannot unlock device.
Command failed.
Serial device: closing device


and after that kernel is saying
cp2101 ttyUSB0: cp2101_set_config - Unable to send request, request=0x0 size=2 result=-32
cp2101 ttyUSB0: cp2101_open - Unable to enable UART
cp2101 ttyUSB0: cp2101_set_config - Unable to send request, request=0x0 size=2 result=-32
cp2101 ttyUSB0: cp2101_open - Unable to enable UART
cp2101 ttyUSB0: cp2101_set_config - Unable to send request, request=0x0 size=2 result=-32
cp2101 ttyUSB0: cp2101_open - Unable to enable UART
cp2101 ttyUSB0: cp2101_set_config - Unable to send request, request=0x0 size=2 result=-32
cp2101 ttyUSB0: cp2101_open - Unable to enable UART