What You Need for This Book

To use this book, I recommend that you have a formatted PC with at least 1GHz of CPU, 20G bytes of disk and 512 Mbytes of RAM. You can also use the free and downloadable VMWare Server (http://www.vmware.com), to install Linux and OpenSER safely in a VM (virtual machine) running inside your own machine. You will have to download the Debian distribution of Linux (www.debian.org). I used the version 4.0R3 (etch) to test the labs. All the software used in this book is freely available on the Internet, so in the proper chapters you will find the instructions on how to download and execute. You will need at least two SIP devices to test most of the labs. I use two PCs with a free SIP softphone and OpenSER in a virtual machine. For the PSTN and Voicemail chapters, you will need to use an external gateway, usually an Asterisk Server. In my testing environment I used a second virtual machine using VMWare server. If you are going to use VMWare, be sure to disable desktop firewall, a good source of headaches for labs.