Are there solitary waves in $phi^4$ theory in 3+1 dimensions?

In 3+1 dimensions with signature +1 -1 -1 -1,

$$\mathcal{L}= \frac{1}{2}\partial^\mu\phi\partial_\mu\phi -\phi^2/2 -\phi^4/4$$

field equation: $$\square\phi+\phi+\phi^3=0$$ (check this)

$$\square=\partial^2_t-\nabla^2$$

Note that it is not a Mexican hat. I guess this haven't been solved exactly before but, somebody have shown or discarded that there could be soliton solutions or at least solitary waves?