To configure or set up, particularly a complex machine with many configuration options (especially knobs and dials).
Before starting the recording, make sure you've dialled in the right synthesiser settings.
To connect to a system or service by telephone.
I tried dialling in to the server, but I couldn't connect.
To join or participate in a conference call.
Did you dial in to that earnings announcement?
To apprehend and align oneself (to an idea, circumstance, way of thinking, etc.)
Nowadays most people are dialled in to the idea that smoking is bad for you.