Simple approximation for Erlang B formula

The Erlang B formula is one of the most important formulas in the field of telecommunication. In this paper a simple approximation for the Erlang B formula has been presented. The accuracy of the produced approximate formula has been investigated. In various problems of communications it is often required to calculate the inverse Erlang B formula. Using the offered approximation the explicit expressions for estimation of the inverse Erlang losses function have been offered.