The different types of cellular signals are: Intracrine signals (this signal is produced by the target cell that stays within the target cell), Autocrine signals (this signal is produced by the target cell, are secreted, and this can affect the target cell itself via receptors). Cells can comunicate with one another through direct cell membrane contact or the cell can release signal molecules into the blood stream.
Hope this helps!! (if it doesn't I'm sorry!)
