It largely depends on what model of switch the phones are connected to, however here are some links to user card and voicemail instructions, hope it helps.
To listen to your messages:
A number of options are available to you during and after listening to a message.
The table “Listening to your mailbox messages” shows the options and when they
1. Press ƒ·°⁄ to open your mailbox.
2. Enter your mailbox password and press OK or £.
3. Press PLAY to listen to your messages. For options,
refer to the table "Listening to your mailbox
4. Press ® to end the session.
Listening to your mailbox messages
Option Button Available
listening to a
X Rewinds the message nine seconds and
resumes playing it from that point.
X X Sends a copy of the message to one or more
mailboxes. When you record the introduction
to the forwarded message, the introduction
must be more than three seconds long.
> >> > >>
X Skips to the end of the message.
Envelope † X X Plays the information on the message envelope.
Envelope information includes the date and
time the message was sent and, if the message
was internal, the directory name of the sender.
This option is not shown on the display.
X X Deletes the message currently being played or,
if no messages are playing, deletes the
message just played. Deleted messages remain
in your mailbox until the session is ended.
(Refer to Notes 1. and 2.)
X Advances the message nine seconds and
continues playing from that point. A message
can be forwarded as many times as required.