Record voicemail for line 2 on 1070 small business system

We are able to set up a custom recorded voicemail for when someone calls in on Line 1, but if they call in on Line 2 they get this terrible automated voicemail. How do I go about changing the voicemail message when someone calls into Line 2? (For example, if they call when someone is already using line 1 - both lines are the same phone number)