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.
If you want to set up Calculate Directory Server as an IP dial system, you should use Asterisk, a software implementation of a telephone PBX released under the GPL licence, that supports various VoIP protocols.t this stage, your users in Moscow are already able to call each other, but you also have users on the Saint-Petersburg server they should be able to join as well. To allow this, you have to set up a connection between your two Asterisk servers.