The day after T-Mobile tried to undercut all the competition by touting a $5/month lease for the iPhone 6S, Sprint is cutting even further, offering the new Apple phone for only a buck a month.

Per the company’s announcement, the deal will be available at Sprint-branded stores starting tomorrow, Sept. 25, for anyone who trades in an iPhone 6.

Since the 6 is barely a year old, most people who currently own that phone are probably still either under contract or still have monthly installments to go before they own the device outright.

That means Sprint won’t be overloaded with customers only paying $12/year for a phone that retails for around $650. And the iPhone 6 devices that are traded in are still new enough to be resold on the secondary market as used phones or be refurbished and handed out as insurance policy replacement phones.

If you want the iPhone 6S Plus or a 6S with more memory, you’ll have to pay more for this offer. The 64GB 6S leases for $5.77/month; $10.53 for the 128GB version. The 6s Plus starts at $5/month, increases to $9.77/month for 64GB and $14.53 for 128GB.

Though Sprint’s program is called “iPhone Forever,” meaning you’ll just trade in this phone when you’re done with it and get the newest version, the $1/month price may not be forever.

As we noted earlier this week, the fine print on iPhone Forever is that the “Forever” applies to the customer’s ability to upgrade, and notes that the “Upgrade does not include same generation model iPhone. Does not guarantee monthly payment amount, phone selection, or service plan rates.”

There also appears to be a 22-month minimum for the lease, and if “service or lease is cancelled early, the remaining lease payments become due immediately and customer must return the device or pay the purchase option.”

It’s unclear if that means the customer would have to pay just the remaining payments of $1/month, or if they would be required to pay the full retail price for the phone. It’s certainly a question worth asking at the Sprint store before you switch service, especially if you’re unfamiliar with Sprint’s coverage in the areas you need service most.

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