G.729 reduces the network bandwidth used by each VoIP call, without sacrificing call quality. Audio compressed with G.729 uses only 1/8 the bandwidth of standard G.711 audio, which allows for more calls to be carried without increasing network capacity and allows voice to travel on limited-bandwidth connections that would otherwise not support VoIP.
Add fax capabilities to your Asterisk or Switchvox system with Digium's Fax For Asterisk (FFA). Fax For Asterisk is a commercial add-on module that lets Asterisk and Switchvox systems send, receive and relay fax documents. Fax For Asterisk supports both traditional analog and SIP (T.38) faxing and can scale from a single channel to many concurrent faxes, making Asterisk the perfect platform for building powerful fax solutions.
The DPMA is a binary Asterisk module that provides a secure communications channel between Digium phones and Asterisk. This secure channel is used to provision and manage the phones and to provide direct access to Asterisk's internal applications.
The DPMA is not required to use Digium phones, but provides the Digium phones with many enhanced applications incuding user presence, visual voicemail, parking, queues and one-touch recording.
Nothing ruins a phone call quite like an echo on the line. Digium's High Performance Echo Cancellation (HPEC) module can help eliminate the most common types of echo heard on PSTN connections. If your Asterisk system's PSTN connections have echo and your interface card does not include hardware echo cancellation, try HPEC.