For data jacks that VoIP phones run on you can essentially have an unlimited number of phone lines associated with one device. By installing a 6 line phone and then adding on sidecars you can ensure that multiple lines will appear on the single data jack.
For traditional analog/Centrex jacks you can install four phones on the voice port of a jack. For example, two phones, one fax, and a credit card machine.
October 03, 2012