  Detection of signals from a possible extrasolar technological civilization is
one of the challenging efforts of science. In this work, we propose using
natural telescopes made of single or binary gravitational lensing systems to
magnify leakage of electromagnetic signals from a remote planet harbours an
Extra Terrestrial Intelligent (ETI) technology. The gravitational microlensing
surveys are monitoring a large area of Galactic bulge for searching
microlensing events and they find more than $2000$ events per year. These
lenses are capable of playing the role of natural telescopes and in some
occasions they can magnify radio band signals from the planets orbiting around
the source stars in gravitational microlensing systems. Assuming that frequency
of electromagnetic waves used for telecommunication in ETIs is similar to ours,
we propose follow-up observation of microlensing events with radio telescopes
such as Square Kilometre Array (SKA), Low Frequency Demonstrators (LFD) and
Mileura Wide-Field Array (MWA). Amplifying signals from the leakage of
broadcasting by an Earth-like civilizations will allow us to detect them up to
center of Milky Way galaxy. Our analysis shows that in binary microlensing
systems, the probability of amplification of signals from ETIs is more than
that in single microlensing events. Finally we propose target of opportunity
mode for follow-up observations of binary microlensing events with SKA as a new
observational program for searching ETIs. Using the optimistic values for the
factors of Drake equation provides detection of about one event per year.
