In this chapter, we built another very useful project for secret agents; a project where you can open a door lock by sending a secret code by SMS. You can also use this project for many other purposes. For example, you could use the same project to remotely activate an alarm when a text message is received by the project.

Note that you can also use the FONA shield to actually send text messages, which opens the door to even more exciting projects!

In the next chapter, we are going to see how to build a typical secret agent project: a remote spy camera that can be monitored from anywhere in the world!