A human engine has a torque curve similar to that of a steam engine, more or less, which is to say that it is flat until a certain critical rpm, at which point it begins to drop off, because the energy used in accelerating and decelerating massy components (legs) begins to take up all the energy produced.
Asterisk is known to run on many OS platforms. However, Linux is the main platform for development and Digium hardware support. If you are running VoIP only, or if you are comfortable with using external media gateways to connect conventional telephone equipment, then you have more systems to choose from, like FreeBSD, Mac OS X and Solaris.
Dumb Maps  discusses vector data structure and its implications. Raster Features  discusses raster data structure and its implications. Converting Between Lines and Squares  identifies procedures for converting between vector and raster. Workspaces  discusses overall GIS data organization considerations.