what documents you have been reading Vijay :-)
Anyways, in simple terms, Regions help you select codecs for calls between two regions. You specify codec bandwidth 8kbps, 64kbps etc. for calls between two regions, so the calls between those region will use the codec equivalent to that bandwidth or less than that. for example, if you setup bandwidth to 8kbs, it will use G729, ilbc etc but never use G711.
While location is used for CAC (call admission control), i.e it specifies maximum amount of bandwidth for a location, which will in turn determine total number of on-net calls that can be made over WAN from that site. If anymore calls are made either calls are rerouted through PSTN if AAR is enabled (or calls fail)
Basically its a QoS mechanism used to control number of audio and video calls that could be made over a particular site's WAN link, to avoid over-subscription of WAN link and preserve quality of the calls.
-Terry
