If I were trying to let intelligent life elsewhere know that I exist and that I am intelligent I would have to create a patterned noise that distinguishes itself from natural noises that could be formed spontaneously. Talk about a challenge!
I believe the standard solution is to send a sequence of signals with durations being consecutive prime numbers (multiplied by some unit of time, but that's irrelevant).
The canonical answer ("Yes, I am very smart too") is to reply with a continuation of the sequence where the transmission stopped.
