suse 11.0 keyspan usa-19hs = problem

After I plugged keyspan usa-19hs into one of my vostro1310 I can see it after lsusb

Bus 006 Device 003: ID 06cd:0121 Keyspan USA-19hs serial adapter

I am trying to talk from laptop through keyspan to GSM modem. Keyspan runs on /dev/ttyUSB0. Now I type

stty -F /dev/ttyUSB0 raw clocal cs8 -cstopb -parenb ixon 115200

I open second terminal and I type

cat < /dev/ttyUSB0

I power up the modem and can see

AT-Command Interpreter ready
A

Please not that for some reason there is ‘A’ in a new line. After that whatever I send to the modem I can only see LED blinking on the keyspan. I have looked at voltages at modems RX/TX and it looks that something is incomming (voltage changes) on RX, but the modem does not reply. So to try is there anyting going out from the modem I ring it (as default modem sends RING on its TX) and I can see voltage changing on the TX pin. So I would say that there is someting with keyspan - do I need extra software/driver?
Thanks.