Activating a Locked AT&T iPhone with the Simple Mobile Sim Card
Maybe you've seen the commercials as I have and immediately wondered, "Can I activate my AT&T iPhone with Simple Mobile?". The answer is NO WAY! The reason is that Simple Mobile is essentially a TMobile reseller. While they may not be directly affiliated with TMobile, they use the TMobile network to activate their SIM cards. What this means, is that you must have an unlocked iPhone for it to work with the Simple Mobile calling plans.
Simple Mobile Alternative
The alternative to this limitation, is to use the Straight Talk Sim plan. Unlike Simple Mobile, the Straight Talk Sim plan uses both AT&T and TMobile. So you can easily activate your AT&T locked iPhone using the Straight Talk Sim plan. Both are basically the same, buy the sim card, insert it into your phone and activate it. I really like the Straight Talk Sim plan over the Simple Mobile because with Straight Talk, I can easily activate just about ANY phone including those that are locked to AT&T. Now if you've got an unlocked iPhone and are in a TMobile calling area, then you can also use the Straight Talk Sim plan as they have SIMS that will work on TMobile as well.
I am partial to Straight Talk because I know their coverage area is the best in the prepaid world. I also like the flexibility of being able to activate my AT&T phone without having to unlock it. Simple Mobile looks promising and it is $5 cheaper than Straight Talk but I don't like the fact that it will only work with an unlocked phone.