The fax4j project has moved to github at: https://github.com/sagiegurari/fax4j
Latest release is no longer hosted here, instead go to: https://github.com/sagiegurari/fax4j/releases/latest
The SFF tools allow you to deal with group 3 fax documents that are stored in the "Structured Fax File" (SFF) format that is produced by most ISDN devices that adhere to the CAPI specification (see http://www.capi.org).