josh_marchant,
To clarify this a little more, the location that you mentioned [Voice Processor > Application-Related Information > Auto Attendant Information > Auto Attendant Transfer Prompt' is already set to No] would be if the extension the Voice Processor is transferring to doesn't have an Extension ID or a Mailbox.
If the extension you are transferring to does have an Extension ID or a Mailbox then you would need to go into that to ensure that the Auto Attendant Transfer Prompt is set to NO; by default it is YES.
Thanks,
TE