I just got my Nexus One and I popped in my T-Mobile SIM card.
I had called Tmobile to ask them what I would need to do to get internet on my N1 and they said that I can just ask them to change it to the plan for 24.99 a month (my BIS is currently costing me 19.99 a month), and I was okay with that.
The rep also said once I get my N1 if I try to go to the browser, it'll automatically tell me to change the plan to get the 24.99 unlimited internet plan...however, when I popped in my sim card and went to the browser, it just went straight to google and I have browsed a few websites....
So I'm wondering if everything is fine and I don't need to call up Tmo and get charged 5 more dollars a month or if I'm getting charged for this. Anyone have any idea?
I think you should be fine. I have a BlackBerry plan on my account and I switch back and forth between Nexus One and Bold 9700 all the time. Haven't had any problems since I started doing this.
You're good. AT&T/T-mobile BIS plans come with BlackBerry & carrier internet. So when you put your sim into another device, it'll use the carrier's internet.