>I´M SEARCHING FOR A LIBRARY TO CONTROL FAX MESSAGES (SENDING AND RECEIVING) FROM VISUAL FOXPRO.
>I NEED THAT CONTROL MULTIPLE COMMUNICATION CHANNELS (ISDN AND MODEMS)

Have you tried using Microsoft's Telephony API (TAPI) services. You'd need the API specifications, but these are widely available, the the required .DLLs including TAPI.DLL (comes with Windows 95).

TAPI can conceptually handle any serial/telephony device including faxes, modems on ordinary as well as ISDN lines. It even has special provisions for such services as real-time feeds. We're using it as a dialer to a real-time stock feed.