QGeoPositionInfoSource::NonSatellitePositioningMethods blocks app

I have the following code (basically starting network positioning and receiving updates):

[CODE]#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
#include <QTimer>

#include <QtCore/QCoreApplication>

#define CELL_UPDATE_INTERVAL 10000

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent), ui(new Ui::MainWindow), cellSource(0)
{
ui->setupUi(this);
QTimer::singleShot(2000, this, SLOT(initCellPositioning()));
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::showExpanded()
{
#if defined(Q_OS_SYMBIAN) || defined(Q_WS_SIMULATOR) || defined(Q_WS_MAEMO_5)
showMaximized();
#else
show();
#endif
}

void MainWindow::initCellPositioning()
{
if(!cellSource)
cellSource = QGeoPositionInfoSource::createDefaultSource(this);

if(cellSource) {
cellSource->setPreferredPositioningMethods(QGeoPositionInfoSource::NonSatellitePositioningMethods);
cellSource->setUpdateInterval(CELL_UPDATE_INTERVAL);
connect(cellSource, SIGNAL(positionUpdated(QGeoPositionInfo)),
this, SLOT(cellPositionUpdate(QGeoPositionInfo)));
connect(cellSource, SIGNAL(updateTimeout()), this, SLOT(cellUpdateTimeout()));
cellSource->startUpdates();
}
}

void MainWindow::cellPositionUpdate(QGeoPositionInfo info)
{
QDateTime time = QDateTime::currentDateTime();
ui->listWidget->insertItem(0, time.toString("hh:mm:ss.zzz"));
if(info.isValid()) {
qDebug()<<time.toString("hh:mm:ss.zzz")<<info;
}
}

void MainWindow::cellUpdateTimeout()
{
QDateTime time = QDateTime::currentDateTime();
ui->listWidget->insertItem(0, "Timeout: " + time.toString("hh:mm:ss.zzz"));
qDebug()<<"timeout"<<time.toString("hh:mm:ss.zzz");
}

[/CODE]

On some devices (old C5, 6710s), instead of giving a positionUpdated signal every 10s, it blocks the application giving as many updates per second as possible. Here is a sample of debug log (I had to kill it quick):
[CODE]
Executable file: 10696 2012-05-16T11:42:39 C:\QtSDK\Symbian\SDKs\Symbian1Qt473\\epoc32\release\gcce\udeb\CellLocationTest.exe
Starting application...
Application running with pid 602.
[Qt Message] "11:42:49.811" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.104" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.129" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.156" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.184" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.213" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.243" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.277" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.309" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.342" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.377" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.413" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.464" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.512" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.559" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.606" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.655" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.702" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.750" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.798" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.810" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.858" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.906" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:50.955" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
[Qt Message] "11:42:51.004" QGeoPositionInfo(QDateTime("Wed May 16 08:42:49 2012") , QGeoCoordinate(62.6, 29.7462, 94), HorizontalAccuracy=168, VerticalAccuracy=230.457)
Finished.[/CODE]

Is there any way of using successfully Network Positioning on the phones I mentioned?