67.3 Generation of Cell Whitelist Events
The cell whitelist events are not generated continually at some fixed intervals. Rather, one event in the enter/exit pair for the technology in use is generated in the following situations:
whenever the device enters or leaves the set of whitelist cells (state change);
whenever a Wait For or Dial activity is encountered in a script (event indicates current state).1
The whitelist feature is thus designed for use together with scripts. The task to be performed should be enclosed in a while loop and preceded by a "Wait For" activity that listens for a whitelist "enter" event (signifying that the device is camping on an allowed cell).
If an "enter" event is generated, the script proceeds through the rest of the while loop, so that the device performs its task once. Then, back at the top of the loop and the Wait For activity, a new whitelist check is done, and so on.