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< User:Heath
Revision as of 22:16, 30 May 2008 by (talk | contribs) (Useful protocols)
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This is probably the only area that I can call myself an expert in.

Asterisk can be made to build a tricked out phone system of any size at a trivial cost.

Ultimately, this page will be a set of config files, patches and dependencies for building such a system.


  • MELP/MELPe - Military grade compression for minimizing bandwidth consumption
  • AMR - What cellphones use
  • g723.1/g729 - What voip phones use
  • iLBC/speex - Open source low-bitrate codecs

Useful protocols

  • Bluetooth will be implemented via chan_bluetooth or chan_cellphone
  • GSM will be implemented with a commercial gateway.
  • Regular POTS service can be done using hardware
  • SIP - VoIP protocol
  • IAX2 - Lightweight VoIP protocol


  • At least a P4 2.4 2GB server with a focus on reliability (solid disk, passive cooling if possible) $1000
  • Backup server/load balancer $1000
  • Half decent switch $300
  • Digium AEX2460E Analog Card 6x4 FXS + Echo can $1800
  • g729 licenses $100
  • 20U Rack $500
  • Rackmount UPS $500


  • Used to switch calls
  • Used to translate between various protocols
  • Used to perform IVR functionality such as voicemail


  • IAX2 has an aes128 option
  • Not all that great in the open source world, but reasonable security can be achieved.