You are correct, G250, G350 and G700s have local recording of announcements which are stored on virtual val or vval. They allow for 20min of total announcement time with 15 playback channels on the 700 and 6 playback ports on the others. If you list integrated announcements the ports of the announcements stored locally on a gateway should start with ggg, where ggg is the gateway number of the media gateway.
Avaya Voice Announcement Manager will allow you to copy, backup, restore, etc. these files.