To use XMPP, you also need to select an XMPP broker. You have to choose if you want to host your own XMPP server under your own domain name or use a publicly available XMPP broker. There are many to choose from.
In this book, we will use the XMPP broker available at waher.se. While not necessary for this chapter, it will help us in later chapters when we introduce provisioning.