From Forum Nokia Wiki

ID	KIS000449	Creation date	October 19, 2006, updated June 25, 2007
Platform	S60 3rd Edition S60 3rd Edition, FP1	Devices	Nokia E60, Nokia E61, Nokia E70, Nokia N80
Category		Subcategory

Keywords (APIs, classes, methods, functions):

Description

APIs are defined in the SDK to asynchronously receive notifications about the status of a WLAN connection (see Connection Monitor API).
However, not all notifications are received as described in the SDK documentation. The following events:
EConnMonBearerAvailabilityChange
EConnMonSignalStrengthChange
are documented to be received asynchronously through MConnectionMonitorObserver::EventL(). Since constantly monitoring bearer availability and signal strength consumes a lot of battery power, automatic notifications for these events are not enabled in S60 3rd Edition devices.
EConnMonBearerAvailabilityChange event can be used for detecting changes in WLAN availability if WLAN background scans are enabled in the device settings. These events may not arrive immediately after the change, since they are restricted by the scanning interval defined in the settings.
EConnMonSignalStrengthChange event is valid only for cellular (GPRS, WCDMA, etc.) bearers.

Solution

If this functionality is needed, applications have to implement their own logic for periodic, synchronous queries for signal strength and/or bearer availability in order to detect any immediate changes.