Ok, before anyone yells at me about thread necromancy, hear me out. It's quite relevant to the topic, I promise!
I'm using the epc.tmobile.com default APN and have been ever since I got my Nexus One. I bought my phone out of contract, so it came directly from Google, not T-Mobile.
I started getting the Web2Go upgrade message in my browser this afternoon. Has anyone else using T-Zones experienced this recently? I'm wondering if they did another pass through user accounts to try to sniff out those still using it for unlimited data.
The only unusual (for me) thing I've done recently was send and MMS this morning (a picture). I almost never do this, and haven't for months. I usually only send plain SMS text messages. I began wondering if perhaps they now key on this somehow and it tripped a flag for my phone's IMEI or something, tagging it as a smartphone that requires one of their current data plans?
I've tried the other APNs, and the only one that sort-of works (I'm encountering problems in some apps, so it may not have all ports open) is wap.voicestream.com. All the others (internet2.voicestream.com, internet3.voicestream.com, epc.tmobile.com) result in no data connectivity and the Web2Go upgrade message in the browser.