  We report on intermittent X-ray pulsations with a frequency of 442.36 Hz from
the neutron-star X-ray binary SAX J1748.9--2021 in the globular cluster NGC
6440. The pulsations were seen during both 2001 and 2005 outbursts of the
source, but only intermittently, appearing and disappearing on timescales of
hundreds of seconds. We find a suggestive relation between the occurrence of
type-I X-ray bursts and the appearance of the pulsations but the relation is
not strict. This behavior is very similar to that of the intermittent accreting
millisecond X-ray pulsar HETE J1900.1--2455. The reason for the intermittence
of the pulsations remains unclear. However it is now evident that a strict
division between pulsating and non-pulsating does not exist. By studying the
Doppler shift of the pulsation frequency we determine an orbit with a period of
8.7 hrs and an projected semi major axis of 0.39 lightsec. The companion star
might be a main--sequence or a slightly evolved star with a mass of $\sim$1
$M_\odot$. Therefore, SAX J1748.9--2021 has a longer period and may have a more
massive companion star than all the other accreting millisecond X-ray pulsars
except for Aql X-1.
