This information is from an australian version, it is not known if it works on any others.
9*762##074 FCN RCL 76 RCL #01
RCL #71
# stores and steps, hold CLR for 2 seconds to get back to TEST mode.
RCL #24 displays ESN
RCL #02 reboots phone
Editor's note: These commands seem to be similar to those used on the P2/P3.
If you have no RCL key use the MEM key instead