Asterisk from Scratch: What you need to know about Asterisk - Session 4 - AstriCon 2014
Asterisk from Scratch is the 2014 edition of the wildly popular Asterisk 1-2-3 Seminar. It is intended to be a well-rounded and informative overview of the Asterisk Project, with a focus on the essentials a general Asterisk "newbie" should know.
Session 4:
Adding logic to the system
Variables
Expressions
Conditional branching
Q&A session