  Raman and combined trasmission and reflectivity mid infrared measurements
have been carried out on monoclinic VO$_2$ at room temperature over the 0-19
GPa and 0-14 GPa pressure ranges, respectively. The pressure dependence
obtained for both lattice dynamics and optical gap shows a remarkable stability
of the system up to P*$\sim$10 GPa. Evidence of subtle modifications of V ion
arrangements within the monoclinic lattice together with the onset of a
metallization process via band gap filling are observed for P$>$P*. Differently
from ambient pressure, where the VO$_2$ metal phase is found only in
conjunction with the rutile structure above 340 K, a new room temperature
metallic phase coupled to a monoclinic structure appears accessible in the high
pressure regime, thus opening to new important queries on the physics of
VO$_2$.
