Replacing a broken BCM. Customer has 11 analog line. They run 3 businesses out of the office. Business A has 4 lines, Business B has 4 lines and Business C has 3 lines. All 11 lines appear and ring on 6 phones. They said that in the past, they were able to have 3 voicemail boxes, 1 per business. My question is, how would that be set up if all lines are ringing on all phones? How would the voicemail know to send line 8 to mailbox B, line 1 to mailbox A, and line 10 to mailbox C?