Kovy,
I remember trying a 4424LD & SOE on a 403 with R3.1(65), it worked, but display function only like a 4424D, extra soft keys did not work either. 4424LD & 4400D were never supported on IP office. I know on R4.0, 4.1, R4.2 the 4424LD is blocked out, it will not work at all!
Andre