Review of an iPhone on Straight Talk. They are a MVNO using the AT&T network and charging a flat-rate of $45 a month for unlimited voice, text, and data....though the data speeds get throttled after 2GB.
9to5mac.com 
Overall, Straight Talk is one of the best iPhone carriers available. The Straight Talk network is pulling from AT&T’s network, so you get full-speed access to nationwide HSPA+, unlimited calling, texting, MMS, and data for less than the cost of a far more limited plan with a post-paid carrier (as well as the convenience of never having to sign a contract). There are a few downsides to using an unofficial carrier, such as the lack of visual voicemail for those who rely heavily on that feature, but the benefits and price seem to far outweigh the downsides.
Sounds pretty good.
Slacker |