I finally got my ATT BlackBerry Pearl 8100 to reliably tether with N810. The connection works every single time, and I get ~20KB/sec transfer speeds.

The trick, as has already been mentioned on this site, is to downgrade Pearl's firmware to version 4.2.1.66. Even though this is an older version, it works fine. I can't tell any difference between 4.2.1.66 and the version that came preinstalled on my Pearl.

Here is how to downgrade:

1) Download the firmware installer here

https://www.blackberry.com/Downloads...87676E90D45F84

(Never mind that the page says v4.2.1.102 and is for Italy, it actually installs 4.2.1.66 on your phone and preserves the US ATT theme).

2) Run the installer

3) Go to C:\Program Files\Common Files\Research In Motion\AppLoader and delete the Vendor.xml file.

3) In the same folder, run the Loader binary. Follow the prompts. The upgrade takes 30-45 minutes. Don't be alarmed if the phone takes a very long time to reboot.

4) Only problem for me was that the browser icon disappeared after the downgrade. To restore it, go to Settings -> Options -> Advanced Options -> Host Routing Table. Find the highlighted entry, bring up the menu (button to the left of the scrollwheel) and click "Register Now".

5) To pair with your internet tablet in OS2008, just use the phone wizard. No need to enter WAP, usernames, or passwords.

Hope this helps.