  We consider a minimal formulation of SO(10) Grand Unified Theory wherein all
the fermion masses arise from Yukawa couplings involving one 126 and one 10 of
Higgs multiplets. It has recently been recognized that such theories can
explain, via the type-II seesaw mechanism, the large \nu_\mu - \nu_\tau mixing
as a consequence of b-tau unification at the GUT scale. In this picture,
however, the CKM phase \delta lies preferentially in the second quadrant, in
contradiction with experimental measurements. We revisit this minimal model and
show that the conventional type-I seesaw mechanism generates phenomenologically
viable neutrino masses and mixings, while being consistent with CKM CP
violation. We also present improved fits in the type-II seesaw scenario and
suggest fully consistent fits in a mixed scenario.
