All phones light screen backlight when call is hung up.

[Bobcat19]

Hi there, I've got a bit of a strange issue at one of our customers who are currently running 5 T27Ps, and one W52P.

Everything works as expected, however there is one strange problem.

All the phones are in the same ring group, so they ring, someone takes the call, that works fine. Now when that person hangs up that call, all of the screen backlights on the rest of the T27Ps turn on.

So they'll be working away, all of a sudden the phone lights up (the screen), because someone else hung up a call.

All of the phones monitor each other with BLFs if that helps or makes a difference.

Is this something anyone has encountered before? And if so, what was the fix?