If you still have your 2G iPhone and have upgraded to the 3G S or even the 3G, you can get a new sim for your 2G iPhone. Activate the 2G iPhone in iTunes and when it asks for your current number, type it in. Complete the process and your old "new" 2G phone will activate giving you the old 2G data plan price tag of $20 including 200 SMS or whatever you choose. Now take the sim out of your 2G phone and put it in your 3G or 3G S phone and enjoy. I did this accidentally last week when I bought a 2G iPhone and I was trying to activate it. My new month went into effect yesterday and it lists my data plan as 450 anytime minutes with 200 SMS included free. Two year contract didn't start over and my eligibility still shows 11/10. By the way, AT&T no longer offers Pay As You Go plans for the 2G iPhone.