To restore factory defaults on Cisco Unity Express firstly take the module offline by typing “offline“, then when confirmed issue the “restore factory defaults” command.

An example follows :

Router# service-mode  service-engine 1/0
Trying 192.168.n.3, 2006 ... Open
se-192-168-n-3# offline
!!!WARNING!!!: If you are going offline to do a backup, it is recommended
that you save the current running configuration using the 'write' command,
prior to going to the offline state.

Putting the system offline will terminate all end user sessions.

Are you sure you want to go offline[n]? : y
se-192-168-n-3(offline)# restore factory default
!!!WARNING!!!: This operation will cause all configuration and data
on the system to be erased. This operation is not reversible.

Do you wish to continue[n]? : y
Restoring the system. Please wait .....done
System will be restored to factory default when it reloads.

Press any key to reload:

System reloading ....

se-192-168-n-3(offline)#
MONITOR SHUTDOWN...
INIT: Sending processes the TERRestarting system.

-- SNIP --

INIT: Entering runlevel: 2
********** rc.post_install ****************

IMPORTANT::
IMPORTANT::    Welcome to Cisco Systems Service Engine
IMPORTANT::     post installation configuration tool.
IMPORTANT::
IMPORTANT:: This is a one time process which will guide
IMPORTANT:: you through initial setup of your Service Engine.
IMPORTANT:: Once run, this process will have configured
IMPORTANT:: the system for your location.
IMPORTANT::
IMPORTANT:: If you do not wish to continue, the system will be halted
IMPORTANT:: so it can be safely removed from the router.
IMPORTANT::

Do you wish to start configuration now (y,n)?

Once this has completed you proceed to setup the hostname, whether to use dns and ntp settings. After this configuration the booting process can take quite some time !