Hi, thanks for the BSP links. Essentially they say both 82 blocks are the same, the 82B just exposes some speakerphone leads. This is what happens when the connecting blocks are switched: Using the 82A with several 2565s and the speakerphone would not turn on. Heard the click in the loudspeaker but no light on the transmitter and it just did not work. I changed the block back to an 82B and it worked fine. I tried different working 4As with the same result. So I'm open to the easy path of just using 82Bs!