AllThingsD:

“We will be offering the benefit of our unlimited plans that start at just $69.99,” said spokeswoman Michelle Leff Mermelstein. Sprint’s $69.99 plan includes unlimited data and 450 voice minutes as well as unlimited mobile-to-mobile calling. Unlimited calling and data costs $99.99 a month. (Update: Those prices don’t include a $10 per month surcharge for smartphones, so iPhone users will really be paying $79.99 and $109.99 for their unlimited plans)

AT&T and Verizon have both walked away from offering new customers unlimited plans, so this could be a significant strategic advantage for Sprint as it gets the iPhone for the first time with the introduction of the iPhone 4S, due next week.