There is therefore a need to forward the message waiting indication data
to Mobile Switching Centers whose service areas overlap with the service
area of the Mobile Switching Center presently serving this mobile
subscriber's wireless communication device. In this manner, any one of
these Mobile Switching Centers can update the mobile subscriber with
regard to message waiting indications. This is accomplished by the use of
the ISPAGE message which is used to forward the message waiting
indication data to Mobile Switching Centers whose service areas overlap
with the service area of the Mobile Switching Center presently serving
this mobile subscriber's wireless communication device.