I went to craigslist and found an 8GB 3G iphone for $150. I borrowed my friends working ATT sim card and took it with me to test in in the iphone to make sure it worked properly. It did. After purchasing, I came home and jailbroke and unlocked the iphone - so it would work on the Tmobile network. The $15 a month unlimited text plan (no contract) is available in the continental US from their website and stores. But you can choose whichever plan that works best for you:
I walked into a local store, asked them about the details of the plan. They verified. I worked with them to choose the number, get the paperwork done, and they told me the total for the sim card, account setup, taxes etc. come out to close to $30. And some of that cash would end up as minutes on the phone. Since it is no contract, the most I could lose is $30 - and walk away. Its worth a shot right? My plan is to use my office phone, free wifi calls via icall, google voice phone, and any other device to make most of my calls. By giving out my google number as my main number, I can get a txt msg of their voicemail immediately on my iphone. I would not take any calls on the tmobile sim unless I wanted to pay the .10¢ per minute charge. I communicate mostly by txt msg, and anything else - I call from other devices. Seems to work pretty well for me so far. Some friends have complained about the amount of different numbers I call from, but thats a small inconvenience compared to the amount of money Im saving! At the very least, its worth a test. FYI - ATT and Tmobile are the only carriers that work on the iphone. Maybe in 6 months, a CDMA version will be released on the Verizon or similar network. Then there will be even more possibilities.