Using your BlackBerry phone as an Internet modem, called tethering, allows you to access the Internet in places you otherwise wouldn't be able to, or would be charged a fee to do so. Using your BlackBerry in such a way is a part of your contract, so no extra fees or subscriptions are needed. Once you have everything set up, it's a simple matter of plugging your phone in and logging on.

Setting Up the Phone

Plug in your BlackBerry to your computer and make sure the BlackBerry desktop application is running. You will not need to install any modem drivers if you have a newer phone or have the latest software updates. They will be installed automatically. In other words, if your BlackBerry can surf the Internet now, you won't need to do anything special to it. Once it is plugged in, simply navigate to the properties menu and select the advanced option. Under the specific carrier heading, you'll need to add a specific command. For T-Mobile, enter +cgdcont=1,"IP","wap.voicestream.com" and for Cingular, add +cgdcont=1,"IP","proxy."

Setting Up the Laptop

Once the phone is set up, you'll need to open your laptop to the Connections menu and select the option to add a new connection. Once there, you'll want to set up the connection manually. You'll be prompted to pick a phone number. For both ATT/Cingular and T-Mobile customers, this is *99#. After this, you'll be prompted to pick a username and password. For T-Mobile customers, choose your T-Mobile name and password; everyone else gets to make one up. Once this is done, simply click through the check boxes and your connection will be created. The final step is to access the options for this connection--under the networking menu, turn off the IP header compression option. Once done, you can surf the Internet.

A Word on Data

While there is no fee for simply sitting idle on the Internet and many carriers have an "unlimited" data plan, there is occasionally fine print that details the carrier's fees for "excessive" use on your part. Before using your unlimited plan regularly as a backup Internet connection, it is best to check with your provider to make sure you won't incur any unexpected fees for surfing the web with your phone as a modem.

Source:

BlackBerryforums.com

BBGeeks.com