After moving to the US from overseas, I needed a pre-paid SIM for my iphone. The at&t go phone SIM was exactly what I needed. After reading the customer reviews, I realised that some people had difficulties activating the SIM and for others it worked well. I thought $6.00 it's worth a shot. The product arrived super fast. I was very impressed. I was sent the cell antenna and the SIM card sticky taped to it (no instructions, cell number or pin). I'm pretty good with using the internet so I found the activation site on the at&t website. The activation went well until the last stage where the data is being processed. I kept getting an error message from the at&t website "error GP038 activation taking longer than normal. Please try again". I tried calling the at&t customer service line but the automated messages ask for a cell number which I don't have. I contacted the seller for instructions and they were very prompt in replying and gave me a web address which took me to the site I was originally at (I was kinda hoping for more detailed instructions). After further detective work and watching "how to" videos on 'You Tube' I found the solution to my problem and got my SIM activated and a new cell number was issued. I think my activation difficulties were to do with at&t (their horrible website) & the fact I had an iphone. Also, worth mentioning I haven't added any credit to my phone as the at&t website doesn't take overseas credit cards. Thus if you're from overseas, the best bet may be to buy a Pay as You Go card as well.