There could be several reasons for this.

First of all, are you sure you have enough credit left on your Three Mobile Broadband account? To check your balance, go to My3 or call our customer services on 500 free from any Three mobile, on 0843 373 0500 from any other UK phone (charged at your standard rate) or on +44 7782 333 500 if you're abroad.

Here are some other things you should check.

• Make sure a firewall is not interfering.

It's possible that your firewall or anti-virus software is blocking access to the internet or interfering with your browser software or 3Connect. You may need to switch it off when installing your dongle software or you have to 'Allow' the software to connect to the internet when prompted.

• Make sure your browser settings are correct.

Computers have many different methods of accessing the internet and the way browsers are set up to access web sites can vary.

• When you're connected to the Three network using 3Connect, please check:
  • The LAN/proxy settings are off.
  • To do this in Internet Explorer, select Tools, then Internet Options and then the Connections tab.
  • Tick the 'Never dial a connection' box and then select LAN Settings.
  • Make sure everything on this page is unticked

• Your browser is not in 'offline mode'.

If your browser is set to work in 'offline mode' you won't be able to browse the internet. To check this go to the setting labeled Work Offline. It's usually located in either the File or Tools menu inside Internet Explorer. Make sure it's not ticked.

• Try a different internet browser.

There are several popular web browsers available on the internet. Some have better methods of connecting to the internet than others. The three most common browsers are:

• Internet Explorer
• Firefox
• Google Chrome

• Make sure you're connected to the internet.

If you're having problems browsing websites, you may want to check you're correctly connected to the internet. To do this, you can run a simple connectivity test. Click here for more details.

There may also be issues with the network. It could be unusually busy, or your computer may have connected in an area with poor coverage.You may want to wait a few minutes or move to another area and then try connecting again.