Amorphous bulk bismuth boron tellurium glass system of compositions (Bi2O3)(x)(B2O3)(0.5-x)(TeO2)(0.5) with x = 0.05, 0.1, 0.2, 0.3 and 0.4 is prepared using melt quenching method. The ac and dc conductivities (sigma(ac) and sigma(dc)) of as-prepared samples are measured in the temperature range 303-373 K and displayed dielectric dispersion in the frequency range 100 Hz-5 MHz. The ac conductivity versus frequency plots were analyzed by considering a power law: sigma(ac) alpha omega(s)(s <= 1). A comparison between values of the index s with those numerically calculated from different conduction models revealed that correlated barrier hopping is a fairly good model to describe the dominant ac conduction mechanism in the studied compositions. Besides, results of the real dielectric constant (epsilon'), loss factor (epsilon ''), and loss tangent (tan delta) together with the optical (epsilon(infinity)) and static (epsilon(s)) dielectric constants, estimated from Cole-Cole diagrams, for the studied samples are given and discussed.