  We show that a site-dependent mean-field approach captures the quantum phases
of the disordered Bose-Hubbard model commonly adopted to describe ultracold
bosons in random optical lattice potentials. The different phases, namely
superfluid, Mott insulator, Bose-glass and -- at finite temperature -- normal
fluid, are characterized by means of the superfluid and condensate fractions,
and compressibility of the system. We point out that both the boundaries of the
Mott lobes and the nature of the phase surrounding them are related to the
spectral features of a purely off-diagonal non-interacting Anderson model. We
compare our results to other works.
