Locating the user
If only mobile users originate calls, then it does not matter where the user is!
However, if we want to reach a mobile user, then:
we can track the user continuously, or
we can start looking for the user where we last saw them and then expand our search, or
we can guess where the user might be based on their patterns of movement (past behavior)
the user tells us where they are
- based on a schedule the user can tell us where they are(e.g., every one minute tell the system where you are now) or
- the user can listen for something which causes them to check in (for example we a page)