Although the plausibility of this scenario is a matter of debate (Vision is no faster than dial-up), one thing is clear: At the time, Sprint did not make DUN-over-Bluetooth readily available to its customers. The Treo 650's Bluetooth preferences screen, for example, provided no option whatsoever for dial-up networking.

Fortunately, a skilled Treo 650 user (known only as shadowmite) spent several hours tracing code and discovered that Sprint had not removed DUN; they had merely hidden it. A two-byte change in the Treo's Bluetooth management code revealed the hidden setting.

With DUN turned on, your Bluetooth-enabled laptop could now get on the Internet anywhere that your 650 could. When Shadowmite posted word of this discovery on the TreoCentral website, the news quickly became a popular thread of discussion.

Eventually, however, users began to report problems after enabling DUN: strange system error messages, conflicts with existing Bluetooth devices (such as headsets), fifteen-second powerup delays, and so on. In light of these issues, abuse of the Vision service was evidently not Sprint's only reason to disable DUN. Obviously, it still had a few bugs.

In June 2005, Palm announced the Treo 650 Updater 1.12. This new version of the Treo's software fixed a number of bugs, and it also added a notable new feature: dial-up networking over Bluetooth was now officially supported by Sprint. Shadowmite's hack is no longer necessary; the DUN option is available in the Treo's Bluetooth preferences panel by default. All you have to do is turn it on! There is even a special icon that indicates when DUN is enabled. Thanks goes to Sprint for keeping their promises.

Today, Bluetooth-over-DUN on the Treo works well, but the configuration process can be a little tricky. This tutorial provides a step-by-step guide on how to connect, complete with pretty pictures. Just follow the instructions below, and you'll be web surfing at the beach in no time.

This guide assumes that you have the following:

Some users claim that DUN works fine with no password, but it would not work for me until I could enter my correct Vision username and password when dialing over Bluetooth. Although you can easily find your username (in Treo's phone application, choose Options then Phone Info), the password is a mystery. According to Sprint tech support, the factory-installed password is hidden and cannot be retrieved, not even by Sprint.

However, you may be able to find out your Vision password if you know your Master Subsidy Lock (MSL) number, which is normally provided by Sprint as part of the phone activation process. (Thanks to Melissa for reporting this tip.) To do so, follow these steps:

You can also change the password yourself online. (Thanks to Mathew Lu for reporting this tip.) Here are the steps:

The changes may take effect in as little as five minutes, although Sprint says it could take up to two hours.

If you have trouble changing your password, Sprint can reset the password for you and give you a new one over the phone. Here's how to do so:

Once you have your new password and have waited for it to take effect, verify that it works before continuing. First, on the Treo, go to the Prefs application, then choose Network.

Click Modify and tell the Treo that it is okay for you to change the settings, then click Password. Enter your Vision password.

The new password should now be assigned. Click Connect.

If you see “Signing on,” followed by “Established,” then everything is working fine.

If you see Error 67, then your password doesn't match the Sprint database. You'll need to wait until the new password takes effect, or check that the password you entered is correct.

Treo 650 users must skip this step.

Treo 700p users, take note! With the Sprint Treo 650, all you needed for Bluetooth DUN was the Vision service added to your normal voice plan. With the Treo 700p, things have changed. Sprint has added special software to the 700p that detects when you're using the Treo to go online with your laptop (as opposed to just surfing on the phone's tiny screen). Sprint calls this kind of access “Phone As Modem,” or PAM, and for some reason they assume that only business users with deep pockets will want it. Therefore, they require you to purchase a special Phone As Modem plan, currently priced at $40 per month in addition to whatever other plan you may already have. That's right: Even if you're paying an extra $25/month for the Power Vision Ultimate Pack, you must still pay another $40/month just to use Bluetooth DUN (no matter how light your usage is). Note that this is the very same feature that comes free (with Vision) on the Treo 650.

Luckily, there is a workaround. TreoCentral member mmastrac has published a hack that allows Bluetooth DUN without the Phone As Modem plan. Here's how to install it:

Treo 700p users must skip this step. (The 700p automatically turns DUN on and off as needed.)

Go to the Prefs application and select Bluetooth, or just click the Bluetooth icon at the top of the Treo's main menu. You should now see the Dial-up Networking option. Turn it on.

Your Treo will inform you that enabling DUN will disable Internet access on the Treo itself. It may also cause other conflicts (such as not being able to send files over Bluetooth) until you turn it back off again.

First, make sure your Treo is on. Then go to the Bluetooth section of your Mac's System Preferences.

Click the Set Up New Device button and choose Mobile Phone.

Wait until your Mac finds the Treo, then click Continue.

Your Mac will generate an encryption key and attempt to pair with the Treo. Your Treo should then pop up a dialog box asking you to enter the passkey. Enter the same number that you see on your Mac's screen.

If pairing is successful, you should then see optional services that you can use with the Treo. If all of them are grayed out, or if you see a message saying no optional services were found, try resetting the Treo and pairing again. (650 users should make sure that the hack was installed and that DUN is enabled.)

Under Mac OS X 10.4, the options for “Dial a specific access number” and “Use a direct, higher speed connection” may not be visible. As long as the checkbox for “Access the Internet” is there, everything should be fine.

Finally, enter your Vision account information. This should be the same username and password specified in the Network preferences of your Treo. For the phone number (also called the “GPRS CID String” on the 650), enter #777. Also, be sure to select “Sprint PCS Vision” as the modem script. If it's not immediately visible, just click the drop-down list box and scroll through until you find it.

If you have completed all of the steps above successfully, you are now ready to connect your Mac laptop to the Internet through your Treo, no wires necessary! First, launch Internet Connect on your Mac.

Switch to the Bluetooth tab and verify that the settings are correct, then hit Connect.

If all goes well, the Internet Connect application should show a connected status like the one below.

Happy surfing!

When you're done with the connection, just hit the Disconnect button in Internet Connect, or choose Disconnect from Internet Connect's menu bar icon.