  We present the clustering of voids based on the quasar (QSO) sample of the
extended Baryon Oscillation Spectroscopic Survey Data Release 16 in
configuration space. We define voids as overlapping empty circumspheres
computed by Delaunay tetrahedra spanned by quartets of quasars, allowing for an
estimate of the depth of underdense regions. To maximise the BAO
signal-to-noise ratio, we consider only voids with radii larger than
36$h^{-1}$Mpc. Our analysis shows a negative BAO peak in the cross-correlation
of QSOs and voids. The joint BAO measurement of the QSO auto-correlation and
the corresponding cross-correlation with voids shows an improvement in 70$\%$
of the QSO mocks with an average improvement of $\sim5\%$. However, on the SDSS
data, we find no improvement compatible with cosmic variance. For both mocks
and data, adding voids does not introduce any bias. We find under the flat
$\Lambda$CDM assumption, a distance joint measurement on data at the effective
redshift $z_{\rm eff}=1.48$ of $D_V(z_{\rm eff})=26.297\pm0.547$. A forecast of
a DESI-like survey with 1000 boxes with a similar effective volume recovers the
same results as for light-cone mocks with an average of 4.8$\%$ improvement in
68$\%$ of the boxes.
