Change Tel.no. voicemail 4645

[StfKdG]

Hi,

We have a 4645 vm system (PBX 4400 Rel 8.0) on internal telephone number 850. In a few weeks we'll need the 800 numbers for a new site. Our company asked me to change the vm number to 990. Is there a simple way to do this without deleting and recreating everyone's mailbox? I want to avoid that all users have to re-initialize their mailbox or lose messages!

Thanks,
Stefan