Da Voismart Knowledge Base.
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.

    e - In addition to the name, also read the extension number to the
        caller before presenting dialing options.
    f - Allow the caller to enter the first name of a user in the directory
        instead of using the last name.