Pretty simple process.
You'll have to enable the announcement board on the g450 first if it wasn't done yet. 'Change media-g x', goto page 2 and set v9 as "gateway annoucements", then 'enable ann Xv9'
Find an available extension, 'add annoucement xxxx', name the announcement, set as integrated, specify the announcement board, F3.
Recording is a separate process but not difficult. I can provide info on that as well.