You need to have Linux, BSD or MacOSX operating system. You need to install following packages before proceeding with the installation of Asterisk.

• Linux 2.4 kernel sources or kernel 2.6 header files. (for libpri)
• bison and bison-devel packages (This is used to build Asterisk)
• ncurses and ncurses-devel packages (Used to build astman, etc.)
• zlib and zlib-devel packages
• openssl and openssl-devel packages