Thanks your all your replies.
The problem has happened on various 3300 systems ( 2 x CXI II's & 1 MXE II) all on V4.2, but also on our test system V5.
The fault is not only connected to the voice mail(embedded) but also when calling out the 2nd digit was a "3" then phone rebooted.
I also like the help these forums provide, have worked on Mitel's since 1988 and you think you know everything until you read these forums.
Regards