Asterisk has a convenient dialplan applications for printing information to the command-line interface, called Verbose(). The Verbose() application takes two parameters: the first parameter is the minimum verbosity level at which to print the message, and the second parameter is the message to print. This extension would print the current channel identifier and unique identifier for the current call, if the verbosity level is two or higher.
The NoOp() application stands for "No Operation". In other words, it does nothing. Because of the way Asterisk prints everything to the console if your verbosity level is three or higher, however, the NoOp() application is often used to print debugging information to the console like the Verbose() does. While you'll probably come across examples of the NoOp() application in other examples, we recommend you use the Verbose() application instead.