This guide is for tethering a Blackberry 8100 v4.2.1107 with T-Mobile service and using the Vista OS SP1 as of 9/16/2008

1.Connect your Blackberry to the computer

2. Open Desktop Manager (this only works with v4.2 or greater)

3. Make sure the Desktop Manager says that it’s connected to your Blackberry.

a.However, if the Desktop Manager does not say that it is connected, something is wrong with your connection, and you need to fix this before you're able to continue.

4. Open your Device Manager (Start>Control Panel>Hardware and Sound>Device Manager)

5. Make sure you have the following in the Device Manager:
+Ports (COM & LPT)
RIM Virtual Serial Port v2
RIM Virtual Serial Port v2
a. If you do not have those Ports, you need to reinstall the Desktop Manager or do a repair on it. The repair is done under the Uninstall screen (Start>Control Panel>Programs>Programs and Features) by attempting to Uninstall the BlackBerry Desktop Software and selecting Repair instead of Uninstall. If the repair does not add the ports, then you need to uninstall then reinstall the Desktop Manager. I had to do that, and it fixed the problem.
6. Close the Device Manager

7. Open your Phone and Modem Options (Start>Control Panel>Hardware and Sound>Phone and Modem Options)

8. Click on the Modems tab at the top, and you should have a “Standard Modem” listed
a.If you do not have the Standard Modem, please follow the steps above. If you already did those steps and still do not have the “Standard Modem” listed, please contact T-Mobile for further support.
9. Select the Standard Modem and click the Properties button

10. Then click on the Advanced tab.

11. There will be a blank box under, “Extra initialization commands:”

12. In this box you need to type the following exactly: at+cgdcont=1,"IP",""

13. Click Ok once that is typed and then click OK on the Phone and Modem Options window

14. Open your Set up a connection or network (Start>Control Panel>Network and Internet>Network and Sharing Center>Set up a connection or network)

15. Select “Set up a dial-up connection” and click Next

16. Select “Standard Modem” and it will progress to the next window that says, “Type the information from your Internet service provider (ISP)

17. In the box next to “Dial-up phone number:” you need to put: *99#

18. In the box next to Connection name and put what you want to name this connection
ie: T-Mobile, Blackberry, Internet etc.
Note: You will not put in a user name or password, so leave those spaces blank

19. Click on the Connect button. It will probably say “The Internet connectivity test was unsuccessful”, so when that window comes up, select “Set up connection anyway” then click Close.

20. Open the Manage network connections (Start>Control Panel>Network and Internet>Network and Sharing Center>Manage network connections)

21. Select the connection you just made, right click on it and go to Properties.

22. Under the General tab, click the “Configure…” button and uncheck the following:
Enable hardware flow control
Enable modem error control
Enable modem compression
23. Click OK once those are unchecked

24. Click on the Options tab at the top of the window

25. Click on the “PPP Settings…” button and uncheck the following:
Enable LCP extensions
Enable software compression
Negotiate multi-link connections
26. Once those are unchecked, Click OK on that window, and then click on OK on the Properties window.

27. Select the connection that was created, right click and select “Create Copy”. A box will come up telling you that Windows cannot create a shortcut here, and ask if you want the shortcut to be placed on the desktop instead, and click Yes.

You have just set up your connection and you are ready to connect.

When connecting, make sure you have your Desktop Manager open, your Blackberry is connected to your computer, and the Desktop Manager says that it’s connected. Open the connection that you created on the desktop and click connect. It will dial the connection and allow you to connect; however there are a multitude of errors that can come up. If you experience or have any issues that do not allow you to connect to the internet, contact the T-Mobile Blackberry support team, and they will assist you. Make sure you don’t call from your Blackberry though, there may be something they need to do on the phone in order to get the connection to work!

I hope this helps everyone! Please enjoy!