  Here we report on Landau level spectroscopy in magnetic fields up to 34 T
performed on a thin film of topological insulator Bi$_2$Te$_3$ epitaxially
grown on a BaF$_2$ substrate. The observed response is consistent with the
picture of a direct-gap semiconductor in which charge carriers closely resemble
massive Dirac particles. The fundamental band gap reaches $E_g=(175\pm 5)$~meV
at low temperatures and it is not located on the trigonal axis, thus displaying
either six or twelvefold valley degeneracy. Notably, our magneto-optical data
do not indicate any band inversion. This suggests that the fundamental band gap
is relatively distant from the $\Gamma$ point where profound inversion exists
andgives rise to relativistic-like surface states of Bi$_2$Te$_3$.
