7.1. Hacks 88100: Introduction
If you've been involved in Linux VoIP hacking for very long (hey, you made it to Chapter 7, so you've been around a while), you're probably already quite familiar with Asterisk, the open source PBX (and the predominant open source VoIP platform). Aside from Asterisk, tons of open source voice networking projects are out there, including OpenH323, GnuGK, sipX, SIP Express Router, OhPhone, SaRP, and GnoPhone. Try Googling some of these. You'll find there's enough open source VoIP stuff to keep you busy for a while.
New VoIP projects arrive weekly at SourceForge.net, so this chapter represents only a partial smattering of what's out there. There's no question that the open source world is a voice hacker's paradise, a realm of mission critical, high-stakes, real-time applications with very little tolerance for underperformance, and SourceForge is crawling with new ways to take advantage of real-time, converged networks for mission-critical voice apps.
Being a voice hacker is sort of like being a network marine. You've got to train hard to spot issues that don't show up in other, less loss-sensitive kinds of networking. You've got to be "first to fight" when problems occur on a voice network, because voice users will pick up on network slowdowns and outages before plain-old data users. It takes thick skin and quick thinking to join the ranks of the voice hacker.
I've saved some of the coolest and toughest "hard-core hacks" for the last chapter because I wanted to ease you into them. You'll need a pretty good understanding of the Session Initiation Protocol (SIP), Asterisk, and Linux to get through this chapter unscathed. So, if you haven't read the first six chapters, it would be a good idea to do so now. Have some fun with those hacks, and when you're ready to get serious, come on back.
Do you want to build and harden the ultimate PC-based telephone server? Do you want to master the old VoIP standard, H.323? How about building a fax-to-email gateway? How about building a PBX server with no hard disks, or bridging a SIP network with the Skype network?
I'm willing to bet you'll rise to the challenge.