You can also define an xml application which will prompt for a name to search and will call a script on a server which will return suitable xml for the phoneboo as described by Konstantin.It's very useful if you have a directory which has more than 1...
If you have asterisk pbx installed it can convert any file format it understand to ring tone format which is g726-32.Using the cli it's done by file convert PATHTOORGINALFILE.wav PATHTODESTFILE.g726-32Worked for me
