Hello, I recently chose to downgrade my iPhone 3G to 3.1.3. After I had restored my pwange IPSW, I could not get signal on my 3G. A friend borrowed me her old 2G iPhone. When I restored and JB the 2G I asked it to skip activation. I inserted my SIM and everything was cruising as fast as 2G does... I tried rebooting, re-seating the SIM, reseting network settings, and nothing worked.. I then restored the 3G and let iTunes do it's activation thing, and it worked. Anyway, long story short, a Rep at AT&T tried to tell me that inserting a 3G SIM into a 2G device destroys the SIM, and that I would need to replace it. I was under the impression that all SIM cards were the same, and just took advantage of the functionality that the handset provided.. Anyone an expert in this? Also, since I am an AT&T Customer, would I ever need to be concerned about the baseband? Or is that only a concern for people who unlock for other providers? She also told me that the 3G data plan was incompatible with the 2G. I used the 2g without issues for 3 days.. is there any legitimacy to this? Lastly, would there be any problem with using the 2G as my "weekend phone"? as a college student, I don't need to be dropping my 3G into a pitcher of beer.. What i mean to say is, would AT&T have issues with this? Thanks in advance!