Expert: DebiN - 8/21/2009

Question
Last week I decided to get an AT&T Go Phone, as I liked that they had the "Pick Your Plan" plans. I went in with the idea that I would buy the cheapest phone and later purchase an AT&T phone off of eBay and just pop my SIM card in. Before forking over money to a stranger to find out whether or not it would work, I tried a few other things. My dad has a Motorola V180 from what was Cingular, but now has AT&T. I inserted my Go Phone SIM card into his phone and it gave me the message of "Unregistered SIM". Okay, maybe his phone is too old, I thought. His SIM card was one I never saw before, either. I had Cingular from 2003-2007, and I had never seen any like his SIM card in any phones of my friends who also had Cingular. So then I tried my friend's Pantech Matrix she bought earlier this year. I put my SIM card in and it said "Reading SIM" for about a minute before I turned it off and gave up. So, my question is, do I have to get an Unlocked phone? I know the phone I have now (Samsung A167) is a dual-band 850/1900 phone, which I've noticed most of the other Go Phones are. But now on the AT&T website there is the Refurbished Sony Ericsson W350, which is tri-band 850/1800/1900 and the Refurbished Motorola EM330, which is also a tri-band, but its band is 900/1800/1900. So what is it that they do to these phones to make them work for the Go Phone plans? Does their band NOT have anything to do with compatibility? I didn't think that my SIM card was different from non-Go Phone AT&T SIMs, but clearly I don't know because there seems to be no distinct pattern of which phones work or not. What I want to know is how to pick out a new phone to work without having to switch to a different plan and re-sign up at the AT&T store. Hope you can help me out. Thanks a lot for reading all of this.

Answer
Your Go-Phone SIM will work in any SIM unlocked GSM phone that works on the 850 and 1900 bands. The reason it didn't work with your father's phone is because his phone is locked to the network and a GoPhone SIM doesn't work with a Cingular branded or AT&T branded phone that is locked to the post paid network. All AT&T phones (whether post paid or prepaid) work on the 850 and 1900 bands (the refurbished EM330 works on 1900 and 850 also in the US, if it showed 900/1800/1900, that was a typo), the trick is that all AT&T and Cingular branded phones are SIM locked and you can't use a prepaid SIM with them. You need a SIM unlocked phone or an AT&T GoPhone from AT&T. I hope this helps. Thanks. DebiN