Radionics D7212B1 Panel Help

["WYSIWYG" <nospam@xxxxxxx>]

I recently purchased a Radionics D7212B1 panel from my local surplus store
in the hopes of building a simple, non-monitored alarm for my house. The
board is dated 9743 and numbered 7212. The EPROM on the board is labeled (C)
Radionics 1995, D7212B1 U4, 26-06962-0316. The Lithium back up battery was
shot (<0.5Vdc) so I replaced it with a fresh one. The board seems to power
up and run. It beeps, the LEDs blink, it seems to respond to a battery being
attached, it answers incoming calls, data and power appears to be on the
Peripheral device connection pins. However, when I connect a D1255 panel to
it, the panel displays "Call For Service" about a minute after power on. The
manual says this means no communication is established between the D7212 and
the D1255. Is there something I need to do to get this to work so I can use
it?

Thanks.

Bob