The call opens by saying how many messages are waiting; nothing plays until you press 1; then the new messages play in turn. While a message is playing:

Key What it does
1 Hear the message header
2 Hear the body
3 Hear the attachment: says if there is one, and plays it if it is a .WAV file
4 Previous message
5 Reply: record after the tone, press # when done
6 Next message, saved or not
7 Delete (press 7 again to restore)
8 Save
9 Advanced menu
* Back to the main menu

Only 5, 7 and 8 count as acknowledging a message. The others move around or play things; they do not stop the callbacks.

The advanced menu (9) is flood control from the handset, useful at 3 a.m.: 9 then 1 blocks the sender and creates the matching filter for you; 9 then 3 deletes every unread message from the sender you are listening to.

The main menu, which you reach with * or by dialling in: 1 hears all new messages, 2 marks all new messages as read (they cannot be played by phone afterwards), 3 opens the saved-message folder, 5 identifies the current mailbox, 6 moves to the next one, 9 repeats the menu.

One caution on main-menu 2. It clears the queue from the phone, and afterwards those messages are readable online but no longer playable by phone. It is not an acknowledgement: only 5, 7 or 8 on an individual message counts as one.