The mgetty package contains an intelligent getty for allowing logins over a serial line (such as through a modem) and receiving incoming faxes. The companion program sendfax is used for sending faxes from the commandline or from other applications. The third main component is vgetty/vm which can be used with a voice-capable modem to implement an answering machine, a voice menu system, and similar things.
fax2png extracts a specified page from a 1-bit black and white TIFF image, such as a fax, and efficiently converts it to PNG format without the performance overhead of netpbm-based solutions. Antialiasing is supported to produce attractive reductions to typical Web browser widths. 90-degree-interval rotations and flips are also supported.
alph implements and analyzes historical and traditional ciphers and codes, such as polyalphabetic, substitutional, and mixed employing human-reconstructable algorithms. It provides a pipe filter interface in order to encrypt and decrypt block text to achieve transparency. The program is meant to be used in conjunction with external programs that transfer data, resulting in transparent encryption or decryption of information. The program can thus be used as a mail filter, IRC filter, IM filter, and so on.
astfax allows you to create an email to fax gateway. It processes incoming email messages with attached fax images and sends them out via the txfax module. Asterisk's outgoing call queue is used to initiate the fax call and transfer. The call file generated for the outgoing call queue is in template form, and can easily be updated for any system's configuration. It can be used (for example) with qmail, asterisk, spandsp, and eps to create an email/fax gateway.
Callweaver is a community driven software PBX project. The most important differences between Callweaver and Asterisk are built-in STUN support, the use of SpanDSP for better codecs and full T.38 fax over IP support, Sqlite instead of Berkeley DB, universal jitterbuffer, POSIX timers to avoid Zaptel timing dependencies, greater speed, more efficient dialplan execution, and greater stability.
The Taridium ipbx is a complete software-based VoIP PBX system that replaces a traditional proprietary hardware PBX. It runs on Linux without the need for extra software licenses, and is based on the SIP standard. It supports many phones and is available for free in a 5 user version.