I have a Vodavi 1428 with an additional KSU. The system is currently capable of 20 extensions, however I was told I needed an additional card to take it to 28 extensions. I have looked inside the additional KSU and it has a slot for some type of card. Does anyone know what I need to obtain to gain the last 8 lines?

Thanks,

You need part# 1432-00 a 4 line, 8 station Expander Module. This can only be added to the Expansion KSU. Hope that helps.