Earlier this month, a group of folks at the XDA Developers forums figured out how to share the GPRS / evdo internet on Windows Mobile based phones over a Wi-fi connection. This was unfortunately not possible on smartphones, until today!

I was able to get this working on the T-Mobile Dash (and posted by inital findings here. The main hurdle in the smartphones is the lack of a network configuration panel of any kind. Luckily, all these settings are stored in the registry.

I am not sure how many of the changes I made were actually necessary. These are preliminary instructions that will work, but may require you to perform more steps than are really necessary.

NOTE: These changes will probably break your ability to connect to wireless networks with your Smartphone until reverted!!! Proceed with caution!!!!

Perform the following actions in HKEY_LOCAL_MACHINE\Comm\TNETWLN1\Parms\TCPIP:
(Note: <blank> means to make the value blank, not the string “<blank>”, or a space. Make the field empty.)

Change these Values to:
AutoCfg = 0 (Default: 1)
AutoInterval = 0 (Default: 300)
AutoIP = 192.168.0.1
AutoMask = 255.255.255.0
AutoSubnet = 192.168.0.0
DhcpDNS = <blank>
DhcpEnableImmediateAuto = 0 (Default 1)
DhcpIPAddress = <blank>
DhcpServer = <blank>
DhcpSubnetMask = <blank>
DhcpWINS = <blank>
Domain = <blank>
EnableDHCP = 0 (Default 1)

Note: The only values you should need to change to undo these modifications are in red. the rest are set automatically.

Add the following Values, and set their value as shown:
dword, DefaultGateway = 0
string, IpAddress = 192.168.0.1
string, SubnetMask = 255.255.255.0

Note: I do not yet know what impact these will have on normal wifi connections. They may need to be deleted to restore normal functionality.

You should probably have the ad-hoc network created before starting Internet Sharing. I set mine up with no security because I’m lazy :D.

You will probably need to make sure that the smartphone does not try to connect to any infrastructure (access point) networks. You can either remove their settings, or in Wi-fi Settings, choose “Only device-to-device” in Networks to access.

Now, startup internet sharing using Bluetooth PAN.
Choose “no” if you get the visibility prompt (although it doesn’t really matter).

You may now turn bluetooth off.

Change PrivateInterface (in HKEY_LOCAL_MACHINE\Comm\ConnectionSharing) to TNETWLN1 (for the Dash anyway).

If you haven’t turned Wi-fi on yet, you should do so now. (i am not sure what the ideal time to turn it on is…)

And now, go ahead and connect.

Troubleshooting:

Check the IP address that is assigned to your “client” computer. If it is 192.168.0.xxx, it probably worked. If not, check your registry settings.

Switch to the Internet sharing app, and make sure it still says connected. If it does not, you will have to start it, and edit the PrivateInterface again.

You may need to set up a proxy if you are using T-Mobile. If you don’t know what I’m talking about, you probably shouldn’t be trying these modifications at this point.

Hope this helps somebody else. I will be using it to get internet on my Ipod Touch when I don’t have wifi.