Got a little success...
1. Borrowed a Windows notebook from my office, plugged in the modem and installed windows drivers from the CD, and USB sniffer. While under Windows, the modem connected OK with no errors at a hight speed (yes! that means that the modem itself is OK and the tel line is also OK). Saved the log, copied it to my linux-box, and created a synh file from it (no errors).
2. Copied the synch to /etc/eciadsl, edited the eciadsl.conf, plugged in the modem, and ran eciadsl-start. Wow!
2.1 The modem started to blink with the LED! It did not blink before;
2.2 The script reported a successful synchronisation, the ADSL LED is still "on";
2.3 the tap0 interface appeared;
2.4 ppp started somwhere inthe background;
2.5 tap0 interface disappered, the ADSL LED went "off";
2.6 tap0 interface appeared again, but the ADSL LED is still "off";
2.7 tap0 interface disappeared!!! the ADSL LED is now "on" and not blinking
3, 4 and so on: running the start-eciadsl script again gives me an synchronisation error, the ADSL LED doen not blink (it is either off or on). If I unplug and replug the modem, I can see the same picture -- it synchronises ONCE, tap0 interface jumps, the everything goes off.