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.
Red Hat is the market leader of Linux distributions, with an estimated market share of 67%, according to Gartner. RHEL entered many data centers via support deals with hardware and software vendors, an approach emulated by other Linux distributions. The company employs more developers than other supported Linux vendors.