asterisk users - Dec 2010 - app_voicemail: "3" for advanced options does not have an effect _while_ the vm-message is played

"3" for advanced options does not have an effect _while_ the
vm-message is played. all other options like "7" delete or
"6" next
message are
working. after the vm-message is played, it's working. the question:
is this intentional? or a bug?

the available documentation does not describe this case.

Kristijan