Dial out:

Dial 71, and then the phone number you are trying to reach, then press "Dial".

Dial extension:

Enter your four digit extension, and then press "Dial".

Voicemail:
Press the "voicemail" button.
The default voicemail PIN is 1212.
Listen to the menu instructions to set a custom pin or to listen to voicemails.

Program Hotkey:
Hotkeys are the 6 keys on the bottom right.
You can tab through multiple pages of hotkeys by pressing the red button below the hotkey screen.
To program a hotkey, press a key corresponding to an empty spot on the lower screen.
If you want to program over an already existing hotkey, press and hold the key until the editing screen appears above.
Set the following settings:
"2. Type : Memory Key"
"3. Subtype: Speed Dial"
"5. Name: " - Enter the nickname for the extension which will appear on the hotkey screen.
"6. Tel: " - Enter the 4 digit extension of the phone you are hotkeying.

Press OK to save the configuration of the hotkey.