[code] -= Info about application ‘Directory’ =-
Provide directory of voicemail extensions
Directory(vm-context[|dial-context[|options]]): This application will present
the calling channel with a directory of extensions from which they can search
by name. The list of names and corresponding extensions is retrieved from the
voicemail configuration file, voicemail.conf.
This application will immediately exit if one of the following DTMF digits are
received and the extension to jump to exists:
0 - Jump to the ‘o’ extension, if it exists.
* - Jump to the ‘a’ extension, if it exists.
vm-context - This is the context within voicemail.conf to use for the
dial-context - This is the dialplan context to use when looking for an
extension that the user has selected, or when jumping to the
’o’ or ‘a’ extension.
f - Allow the caller to enter the first name of a user in the directory
instead of using the last name.
So from this I would say that the * or 0 option is what you want.