IP PBX Control Unitfor the KX-TD7896, TD7895, TD7885:When installing on a TDA system it isimportant to remember that phones are exactly like the 7700 series phones, only packed into a portable handheld cordless unit. That means you can only put these cordless units on a TDA50/100/200 extension cards that will accept the 7700 series phones. It is also very important for you to rememeber that Pansonic only supports 3 of the TD7895 or TD7896 on any one system at a time. They will create line noise upon eachother because they are Digital Spread Spectrum. You can put up to 15 of the T7885 cordless on any one system because these arenot as powerful. KX-A242X is the rack mount bracketThe older version of panasonic software limited the number of people in incoming callgroups to 32. However, with the version 3.0 software, the incoming call group can be increased to192.