Well I may be wrong and tell me if I am ok :). But right now radio
waves are the and waves that go tower space right? At lest of what
humans know. So based on what we know is the radio waves are the most
logical wav the ET will try to contact earth. But if we do find
another wav that will travel tower space I am sure we will try to scan
with that also. But how said the ET have to be smarter the us? They
all may not be. So may be I believe, but now all. So that may give you
something to think about.