  We analyse a flavour model for a lepton sector which is based on type I
seesaw mechanism, a Z_2 symmetry for lepton flavours, a mu-tau interchange
symmetry and a CP symmetry. This model fits well the data of neutrino mass
squared differences and oscillation angles. The model predicts an overall
neutrino mass scale for normal and inverted neutrino mass hierarchy and the
effective mass m_beta, which is used in the neutrinoless double beta decay.
