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.

Current version doesn't do GSM. Mainly because I have no idea how to do it.

Compression

• 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

Equipment/Costs

• 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
• Far end server colocation $400/month

Dependencies

• Existing network/Internet
• Cool/dry/secure area
• ~1000 watts available power

Asterisk

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

Security

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

Instructions

• Build servers. Insert Digium card/s.
• Load the ups/servers/patch panels into the rack.
• Connect power; connect servers to switch
• Load Debian or Ubuntu Server onto the servers.
• Follow these instructions - Easy if you've done it a few times.
• Follow these instructions - Have a friend nearby to take your aggression out on.
• More to come...