I recently picked up on eBay a new Focus S. I plopped in my 4-yo at&t SIM card with its $10 "Family Data Unlimited" plan (recently switched from the older $15 mediaNET unlimited plan), but the cellular data is not working at all. Right now I'm getting data only through WiFi. What gives?! This SIM card was giving me 3G data on my hp Veer and Palm Pixi Plus, but not on my Focus S. Is it because the latter phone is HSPA+? That can't seem to make sense because the Veer is, too. Is there something about Windows Phone 7 that allows at&t block data going through the old mediaNET SIM card? I need a solution, and don't want to walk into AT&T mobility and have them convince me I need to buy their newly increased $20 smartphone data plan. Does IMEI or APN matter here? Any advice would be much appreciated!