We present a logic to describe communcation channels and secret messages. Additionally, our logic can reason about communication protocols. We combine a Dynamic Epistemic Logic (DEL) perspective with ideas from Interpreted Systems (IS). Our framework models the communication channels underlying the information flow as well as the information flow itself. Our DEL-style actions allow us to model various communication actions such as message passing and group announcements. In particular we define an external informing action, which essentially announces the protocol the agents are supposed to follow, thus making it common knowledge that the future behaviour of the agents is constrained. Our framework is very flexible in modeling a variety of scenarios with different assumptions about the observational power of the agents. We propose a generic method of epistemic modeling where the initial model is simply the real world, and other worlds are generated on-the-fly. We show how our framework applies to some nice examples.