Yes, it is possible that aliens or extraterrestrial civilizations could be communicating using wavelengths that are very different from those commonly used on Earth. The concept of communication is not limited to a specific range of wavelengths or frequencies.
On Earth, we primarily use radio waves for long-distance communication, as they can travel through the atmosphere and across vast distances. However, there is a wide range of electromagnetic spectrum beyond radio waves, including microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
It is conceivable that alien civilizations might have developed different technologies and communication systems that operate in different regions of the electromagnetic spectrum. They could be using wavelengths or frequencies that are beyond our current detection capabilities or even entirely different modes of communication that are not based on electromagnetic waves.
Moreover, it is also possible that alien civilizations have developed entirely different methods of communication that do not rely on electromagnetic waves at all. They could be using technologies and mechanisms that we have not yet discovered or comprehended.
Speculating about the exact nature of alien communication is highly speculative due to our limited knowledge and lack of empirical evidence. However, considering the vastness of the universe and the potential diversity of life and technological development, it is reasonable to assume that there could be forms of communication occurring in very different wavelengths or using entirely different methods.