[WBFAir]

If I understand correctly, as others here have mentioned, you need to shut off your data connection.

You may find some stuff for this in the regular Comm Manger but even when you set the Data Connection off, it can still work.

Also you could try the connection app, All Settings>Connection>Connections
and see if with in anything there you can set the Wifi connection to have or stay as a priority

For me I tried all that but eventually decided to permanently shut it off on my Verizon TP2 by going to HKLM\Comm\ConnMgr\Providers then go through all the lettered/numbers folders till you find the one that has the AT&T networks in it (usually is the one that they are in a sub folder named “Connections” and in those connections parameters, set Always On to 0 and Enable to 0.

This will completely shut down the connections.

Keep in mind though you will loose the ability for any apps that are hard coded to use those from being able to make any kind of a connection anymore.

Also note that this is my first Reg hack recommendation so I would suggest you double check this with some searches on that reg location and confirm this, also back up your registry before.