Thanks for the info. Can someone buy five lines, pay first month bill and $1000 ETF and cancel the contract getting five SIII for around $1200?
Yes. Which would be a very good deal. Just keep in mind that T-Mobile frowns upon this and will blacklist your SSN if you do this repeatedly. Doing it once every few years should not be a problem - what I'm saying is, don't do this every 6 months to get cheaper phones.
I think as long as you're credit class B (their internal rating, they won't easily tell you what you are) or above, you can do the 5 lines with no deposit. I'm credit class A and that's 10 lines no deposit, I think B is 5 lines.