Dialing into voicemail from your extension:
DIAL *97 and your own extension number
To dial into your voicemail from outside the office:
Call the main company number on your system. When the greeting answers, dial '*97' to be transferred to the voicemail system. Follow the voice prompts to access your voicemail box (remember to use your extension number as your voicemail box number). Note, this only works when company numbers route to a menu system giving you enough time to dial *97.