Unlike your grammar (sigh)....
No you are wrong and the original poster is spot on with his AM/FM radio analogy. T-mobile uses a different frequency for it's 3G so even if you cut down one of their SIM cards you will not be able to get their 3G service.
Verizon and Sprint use a totally different form of 3G so you can never use one of their services with a a GSM data service like the iPhone.
You, young man, are completely wrong.
um hello? that what i said. t-moblies 3g wouldn't work cause its at a different frequency and they dont use microsims. while Verizon and sprint dont use sims at all. learn to read