Sprint vies with T-Mobile by launching $1-per-month iPhone 6s offer

To qualify, shoppers must be signed up for the iPhone Forever program and trade in an old iPhone 6, Sprint said. People getting a 16-gigabyte 6s will end up paying $12 — plus standard monthly service fees — by the time 2016 iPhones are released.

The same deal gets a person an iPhone 6s Plus for as little as $5 per month. Costs rise, though, when choosing models with extra storage. 64- and 128-gigabyte versions of the 6s are $5.77 and $10.53 per month, respectively, and equivalent prices for the 6s Plus are $9.77 and $14.53.

People with an iPhone 5s can trade it to get a 16-gigabyte iPhone 6s for $10 per month, or a 6s Plus for $14 per month. Through Dec. 31, new and upgrading customers will be able to get a $15-per-month rate by turning in any other smartphone.

On Wednesday T-Mobile launched a similar promotion through its Jump On Demand program. Though it doesn't have a $1 price tier, T-Mobile is more flexible in that identical discounts are available for people trading in higher-end Samsung phones, and subscribers can switch away from the iPhone platform later on.

Apple is set to launch the 6s and 6s Plus on Friday. The company is offering an iPhone Upgrade Program akin to Sprint's, but starting at $32 per month with AppleCare+ included.