Partyline: - EB7-4W functionality with the HB-704

EB7-4W is a 4-wire daughter-board designed for use with single and dual channel KB and HB stations. 

When used to connect a four channel HB-704 station, the channel selector on the HB-704 works as expected for channel 1 and 2.
When selecting channel 3 or 4 on the HB-704, you will get the same behavior as when channel 2 is selected (with audio in both directions). 

The complete manual can be found under SUPPORT - MANUALS - ENCORE; 
http://www.clearcom.com/userfiles/file/User%20Manuals/Partyline/Clear-Com_EB7-4W_Manual.pdf