Classical unified field theories describe the properties of the electromagnetic field as a purely geometric phenomenon. Einstein tried to form a generalized theory of gravitation that would unify the gravitational and electromagnetic forces (and perhaps others), guided by a belief in a single origin for the entire set of physical laws. These attempts initially concentrated on additional geometric notions such as vierbeins and "distant parallelism", but eventually centered around treating both the metric tensor and the affine connection as fundamental fields. (Because they are not independent, the metric-affine theory was somewhat complicated.) In general relativity, these fields are symmetric (in the matrix sense), but
Unified communications voice mail from any communication device at any time. It expands beyond voice mail services to data communications and video services. With unified communications, multiple modes of business communications are integrated. Unified communications is not a single product but a collection of elements that includes: "Presence"—knowing where intended recipients are, and if they are available, in real time—is a key component of unified communications. Unified communications integrates all systems a user might already use, and helps those systems work together in real time. For example, unified communications technology could allow a user to seamlessly collaborate with another person on a