  We calculate numerically the probability $\exp[ {1\over\lambda}
F(E/E_{sph},N/N_{sph})]$ of the false vacuum decay in the massive
four-dimensional $-\lambda\phi^4$ model from multiparticle initial states with
fixed number of particles $N$ and energy $E$ greater than the height of the
barrier $E_{sph}$. We find that at $E\lsim 3E_{sph}$ and $N\lsim 0.4N_{sph}$
the decay is classically forbidden and thus is exponentially suppressed. We
argue that the classically forbidden region extends at small $N$ at least up to
$E\sim 10 E_{sph}$ and, most likely, to all energies. Our data suggest that the
false vacuum decay induced by two-particle collisions is exponentially
suppressed at all energies.
