These charges are not actually $ charges, but recorded as internet access under my cell phone number.
This has nothing to do with wi-fi access. This has everything to do with data access via T-Mobile's cellular network when your iPhone has reception with T-Mobile's cellular network.
The iPhone is designed to always have internet access as long as there is an available wi-fi network you have access to if wi-fi access is on, or via the cellular network as long as you have cellular reception with the iPhone switching between the two automatically and seamlessly. When wi-fi access is on and there is an available wi-fi network you have access to, after a period of time after the iPhone has been asleep, wi-fi access is turned off automatically with the iPhone switching to the cellular network when there is cellular reception. When waking the iPhone up, the iPhone will quickly reconnect to the available wi-fi network when wi-fi access is on. If wi-fi access is off and you have low cellular reception, the iPhone will continually try to maintain the cellular connection and reconnect if possible after reception is lost.
These charges are not actually $ charges, but recorded as internet access under my cell phone number. They aren't actually charging me anything for the tiny bits of of access, but I just find it weird that this didn't begin when I first installed the T-Mobile@Home HiPort last April.
Then what are you worried about exactly? The iPhone is designed to always have internet access as long as there is an available wi-fi network you have access to with wi-fi access enabled, or cellular reception.