Nokia 6020 stops responding to AT commands mysteriously (offtopic???)

[Peter Hanula]

I use nokia 6020 for dialup connection via dku-5 cable
(ti_usb_3410_5052 driver). Sometimes it just seems ignore any AT
commands (for example using gnokii model=AT or pppd or minicom or
something). If i set model=6020 it works just fine (but i cannot set
up dialup connection via pppd). When such thing happens only solutuion
is to boot up windows, lauch nokia pc suite, plug and unplug phone
from pc and then plug cable and phone back to linux. Reloading cable
driver, machine reboot, phone off/on, gnokii --reset soft, gnokii
--reset hard, cat /dev/random>/dev/ttyUSB0:) don't help.

I observed this behaviour unpredictably after interrupting ppp
conncection during initializition but also after normal startup
(during previous run everything worked fine).

As usual a apologize for my English... :)

Kernel v2.6.14.4, gnokii v0.6.12

Could you suggest any solution or other place to ask ?