I know this is old...but...

While I can't provide remote support for you, I can confirm that that 8400 series phones will work on this card. The 8400's can be either 2 wire or 4 wire. Just be aware that there is a "bug" on the earlier releases of the 8400 series that could cause the phone to not work on a 2 wire card after it's been used on a 4 wire card.