See this thread about Smartphone support: http://www.b4x.com/forum/showthread.php?t=540
If your device is supported I recommend you to pass the text file to the desktop and then launch a fax program.
Thank you for answer,
but i ask if exist a library like/similar email or ftp or sql ?
i am developing a application "ORDERS" and i already use email dll (library) for send a document text. now i want add a function for send a document through fax.
My device is http://www.clubimate.com/t-DETAILS_JAQ3.aspx
I think that you have no chance to send fax from your device directly.
You should use an email to fax gateway or something more manual.
Send data to a pc through ftp and then fax them with an app like activefax.