  In this paper we present thoughtful comments on the paper `Bessel beams and
signal propagation' showing that the main claims of that paper are wrong.
Moreover, we take the opportunity to show the non trivial and indeed surprising
result that a scalar pulse (i.e., a wave train of compact support in the time
domain) that is solution of the homogeneous wave equation (vector
($\vec{E},\vec{B}$) pulse that is solution of Maxwell equations) is such that
its {\em wave front} in some cases does travel with speed {\em greater} than
$c$, the speed of light . In order for a pulse to posses a front that travels
with speed $c$, an additional condition must be satisfied, namely the pulse
must have finite energy. When this condition is fulfilled the pulse still can
show peaks propagating with superluminal (or subluminal) velocities, but now
its wave front travels at speed $c$. These results are important because they
explain several experimental results obtained in recent experiments, where
superluminal velocities have been observed, without implying in any breakdown
of the Principle of Relativity.
