Thanks but I already did all these settings, my problem now remains that my US Robotics Courier 56K V90 Model: 3453C Business Modem doesn`t do Handshake with PBX modem. I tried with the same initialization string sent from my modem to the PBX modem but unfortunately it doesn`t send anything on the telephone line to the other modem. I tried with differetn software - ZOC, Procomm Plus, Secure CRT, Hyperterminal, TerraTerm - but the result was the same. I checked several times the DeepSwitch position on the Modem and finaly the only good position was with - 1, 4, 6, 7, 8 - ON and 2, 3, 5, 9, 10 - OFF. I made all the other settings similar to the PBX modem, just to make them working in the same range and values both.
I`m not very sure what else should I try.