T-Mobile: There are special discounts for students who are registered with studentrate.com. This includes a $50 credit on your phone bill and a waived activation fee.
AT&T: If your school is affiliated with AT&T Business Center, you get huge discounts off your monthly bill. Check out the Business Center homepage, and enter your email to the right to see if you qualify for discounts.
Verizon: The Verizon student discount is a bit harder to find. Go to its employee discount page and enter in your school email to see if you qualify for up to 20 percent off your monthly bills.
Sprint: Contact Sprint at (888) 457-6294 or firstname.lastname@example.org to see if your school qualifies for the discount.