iPhone 6S Sprint
Customers can lease the iPhone 6S through Sprint for $1 a month with the trade-in of an iPhone 6. Reuters/Beck Diefenbach

A price war is brewing for the iPhone 6S. Not to be outdone by T-Mobile, Sprint unveiled one of the cheapest deals available for Apple’s latest smartphone.

Starting Friday, customers can get their hands on a 16GB iPhone 6S for $1 a month or an iPhone 6S Plus for $5 a month at Sprint with a trade-in of an iPhone 6. Other versions of the smartphone are also available with an iPhone 6 trade-in -- $5.77 a month for 64GB and $10.53 a month for the 128GB model. The iPhone 6S Plus will be available for $9.77 a month for 64GB and $14.53 a month for the 128GB model with trade-in. Customers trading in an iPhone 5S can get a 6S for $10 a month and $14 a month for the 6S Plus.

In comparison, T-Mobile will offer the 16GB iPhone 6S for $5 a month with a trade-in of an iPhone 6, 6 Plus or Samsung’s Galaxy S6 and Note 5 smartphones. However, there’s a caveat for both deals. Sprint’s offer is under its iPhone Forever program -- where customers lease the smartphone for 22 months instead of purchasing it. But when a new iPhone is launched, they will be able to upgrade a year later.

T-Mobile’s deal is through its Jump On Demand program, a similar 18-month leasing plan, where customers can swap their iPhone with any other smartphone up to three times a year. But customers can also choose to purchase it at the end of the lease.

Apple’s iPhone 6S officially goes on sale Friday in Australia, Canada, China, France, Germany, Hong Kong, Japan, New Zealand, Puerto Rico, Singapore, the U.K. and the U.S. The iPhone 6S starts at $649 and the 6S Plus starts at $749 for the 16GB unsubsidized model.