User:Heath/PBX

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.

Compression

• MELP/MELPe - Military grade encryption for minimizing bandwidth consumption
• AMR - What cellphones use
• g72x - 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
• IAX - Lightweight VoIP protocol

Asterisk

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

Security

• Not all that great in the open source world, but reasonable security can be achieved.