Erlang-B: B(n,x) = (xn/n!)/(1 + x + x2/2! + .. + xn/n!) = (xn/n!)/Σ(xn/n!)

n = number of servers
λ = Arrival rate
μ = Service rate
x = λ/μ
x = Traffic intensity measured in erlangs

Erlang-B Numerator [NR] = xn/n!

Erlang-B Denominator [DR] = Σ(xn/n!)

Erlang-B: B(n,x) = (xn/n!)/Σ(xn/n!)

Erlang-C: C(n,x) = n * B(n,x)/(n − x*(1−B(n,x)))