The PBX modules and the login menu¶

Asterisk module¶

frontend/asterisk/ has app_dmodem, a dialplan application that answers a call on an Asterisk channel with the open modem and hands the connection to a server (TCP or a unix socket) or a program on a pty such as pppd, per profile in dmodem.conf, and DModemSendFax and DModemReceiveFax, a group 3 fax machine on the audio or over T.38 (PJSIP). It is built on libdmodem (frontend/dmodemd/dmodem.h, and frontend/dmodemd/dmodem.hpp with C++ classes for it), the modem core and open DSP as a library. Because that puts AGPL code inside a GPLv2 Asterisk module, it is off by default and only for building on your own Asterisk, never to be distributed (LICENSING.md); dmodem-ari, below, is the way to ship D-Modem for Asterisk. See docs/asterisk.md.

frontend/ari/ has dmodem-ari, the same as a program of its own beside Asterisk, an application of the Asterisk REST Interface (ARI): the dialplan's Stasis(dmodem,<profile>) hands it a call, and Stasis(dmodem,sendfax,<file>) or Stasis(dmodem,receivefax,<file>) a fax, whose audio it takes over RTP from an external media channel, or from a SIP leg of its own that can go over to T.38 (t38 = yes). Nothing of D-Modem is loaded into Asterisk. It is a prototype; see docs/ari.md.

FreePBX module¶

frontend/freepbx/ has a FreePBX module (16 and 17) for app_dmodem or dmodem-ari: the profiles edited in FreePBX's web interface, each a destination for inbound routes and IVRs, dmodem.conf and the dialplan written on Apply Config, a fax destination, calls out to a remote modem with a profile (the page or fwconsole dmodem dial), the settings in FreePBX's Backup & Restore, and a check of the PJSIP trunks and extensions for what costs modem calls (other codecs, both G.711 laws, DTMF or fax detection in the audio). cmake --build build --target freepbx_module packs it. See docs/freepbx.md.

FreeSWITCH module¶

frontend/freeswitch/ has mod_dmodem, the same for FreeSWITCH: the dmodem application (a server over TCP or a unix socket, or a program on a pty, per profile in dmodem.conf.xml) and the fax applications dmodem_send_fax and dmodem_receive_fax, on the audio or over T.38 (sofia). See docs/freeswitch.md.

The two modules share frontend/pbx/dmodem_bridge.c on libdmodem's C API: the profile's options, the modem with its DTE on a socketpair, and the data between it and the profile's server (TCP or a unix socket, optionally with the call's details first) or program on a pty. Each module keeps its PBX's side (the channel's frames, its variables and log, the fax applications).

Login menu (optional)¶

modemmenu is a login and menu for callers, in Go: it checks a user name and password against a text file, LDAP, an SQL database or PAM, then offers a BBS, PPP or a shell, started with the caller's credentials, the dialed number, the connect rate and the time of the call. Either module runs it as a mode = exec profile, or connects calls to one modemmenu -serve by a mode = unix profile with header = yes.