According to this thread up on Howard Forums, it appears as if T-Mobile has now shut down port 80 access over T-Zones.

Bummer. Up until last week I could hit any http address from my Audiovox 5600 for only $4.99 a month, unlimited usage. Options? Since T-Zones is locked to WAP only, it looks like you either have to move up to the $19.99/mo unlimited, or use a dial-up connection.

Since I rarely browse the web from the phone, I think I’ll just use dial-up for now. While it’s a lot slower, it’s also a lot cheaper each month.