I have upgraded a 7400 from 4.92 to 5.01 and none of the SMT's will register. I'm getting IPP Registration lock.

I've tried running through the wizard again, passwords are correct. Tried changing from phone password to system password in 5.2.10 no luck!

This is either the white list setting for the handsets or ipp registration is disabled In the system ip options. I think this is dm 5.2.10 from memory. Our mmc codes are different but it's 841 here in Australia