  The classification of gamma-ray-detected blazar candidates of uncertain type
(BCU) is a relevant problem in extragalactic gamma-ray astronomy. Here we
report the optical spectroscopic characterization, using two 3-4~m class
telescopes, Telescopio Nazionale Galileo and Devasthal Optical Telescope, of 27
BCUs detected with the Fermi Large Area Telescope. Since the identification of
emission lines is easier in broad-line blazars, which usually exhibit low
frequency peaked (synchrotron peak frequency $\leqslant10^{14}$ Hz) spectral
energy distribution, we primarily target such BCUs. We found that 8 out of 27
sources exhibit broad emission lines in their optical spectra, 3 of them have
redshifts $>$1 and the farthest one is at $z=2.55$. The optical spectra of 2 of
the 19 remaining objects are dominated by the absorption spectra of the host
galaxy, and there is a tentative detection of the Lyman-$\alpha$ absorption
feature in one source. The spectra of the remaining 16 objects, on the other
hand, are found to be featureless.
