This tutorial is for a 3internet connection, but if you use another network all you really have to change is the APN and username/password.
1.) Insert your dongle into your PC … it should pop up a “New 3G Broadband” window … select the options you need and click next until the configuration is complete. Note that if you have a PIN set on your SIM card (which you REALLY should!) it will ask you for this when you come to connect… Continue from step 2
If nothing pops up, right click the “network Manager” icon in the system tray by your clock, and select “Edit Connections”, click the “Mobile Broadband” tab, click “Add”, select your device from the drop-down menu, click “Forward”, select “Britain (UK)”, click “Forward”, select “3”, click “Forward”, select “Internet” as your Plan and “3internet” as your APN, click “Forward”, click “Apply”… now in the window that opened… Continue from step 4.
2.) Now, before you try to connect (!) you will need to change a few settings … if you right click on the network manager icon in your tooltray (top right) and select Edit connections, the network connections box should appear.
3.) Now click on the Mobile Broadband tab, highlight “3” (or whatever you decided to call your connection when it was auto-added) and click on Edit. Note in the example below I called the connection “Three” rather than “3”.
4.) You should now see the screen shown below … make sure you enter your PIN if there is one set up on your SIM card.
Next you will need to click on the “PPP Settings”, this stage in particular is CRITICAL as to an extent, everything else we’ve done so far is common sense, whereas this is a show stopper unless you know it needs to be changed.
5.) You should now see the second screen as shown in the screenshots at the bottom of this post. First you need to limit the authentication methods to PAP, this is done by clicking on the ‘Configure Methods’ button and unticking the other unwanted methods.
6.) Next you need to turn off compression, in particular leaving boxes here ticked it likely to prevent the system from establishing a PPP connection with Three’s servers, so although you will see a nice clean blue 3G light on your modem, it won’t actually produce a working connection.
7.) Click on Apply and we should be ready to attempt a connection.
8.) Right click on the Network Manager icon in the tooltray and “3” should be listed under the connection name you chose. Select this option.
9.) Connecting will probably take around about a minute assuming it’s working properly.
[smg type=full id=682]
Troubleshooting
a) I’ve waited a minute but I still see a green flashing light and have no connection
- Check you’re actually within range of 3’s 3G service
- Check your PIN setting / make sure it’s clear if you have no PIN
b) I’ve waited a minute and have a blue 3G light, but no connection
- You’ve connected to 3, but PPP failed, so check you’ve turned off your compression settings.
c) I have a connection, but want to disconnect and clicking disconnect on the tooltray item doesn’t work
- yup, bug. Just pull the USB modem from it’s socket, works every time. 
d) It worked once, but now when I try to reconnect it sits there
- it can get confused, try removing the modem, then reboot the PC.
