A method for providing a computing infrastructure based on virtual machines. The directory tree structure includes nodes comprising a collection of related data and branches comprising links between the nodes. The first media controller bridges a first media path between the first and second communication devices and records, into a storage device, media exchanged in the first media path during the telephony call. The plurality of GPS satellite signal receiving antennas are connected pairwise to a phase comparator for comparing a plurality of first phase differences induced by a first GPS satellite signal received concurrently between the plurality of GPS satellite signal receiving antennas.