I called the T-Mobile customer service line and received a clarification about the HotSpot@Home service. The charge for this service is just for unlimited calling at home and at T-Mobile hotspots. If you don’t mind using your regular service minutes in these situations, there is no need to subscribe to the @Home service – you can still use the Wi-Fi connection for better reception. So since I never seem to use more than half my minutes, I cancelled the @Home service. The phone still uses Wi-Fi when it can, so the customer service agent appears to be correct.
This makes me a lot happier with T-Mobile. When the Wi-Fi is being used to offload their network and provide better coverage, they don’t charge for it. This is as it should be. If the offload/coverage effect turns out to be a significant benefit for T-Mobile, and as the price of Wi-Fi in handsets comes down, it is conceivable that T-Mobile will find it worthwhile to add Wi-Fi to all their phones.
I remain curious about why my Nokia 6086 can’t use the Wi-Fi for web browsing.