Sarah, at 2 and a half, I think you have to take a step back and look at him as a whole, not just at night time.
When they are tiny babies, we are used to catering to their every whim, wanting them to feel secure, comforting them, but as they reach toddlerhood we start to teach them that they cannot have everything their own way.
They have to learn to share, they have to learn to eat properly, they have to learn to hold hands near roads etc and they spend their days trying to exert their will. As parents, we have to override this as we know what is best for them (most of the time).
The same goes for bedtime. He is not calling for you because he is frightened, or distressed, he wants to be with you, but he is now perfectly old enough to know that you are still there, in the next room, and that he is not abandoned.
I'm not telling you to CC or not, just saying maybe think about how you would respond to him during the day if he is doing something that you don't want him to.
I am about to start practicing what I preach - wish me luck.