Sprint is joining in with its own early upgrade plan after its three primary competitors launched new services this summer allowing customers to get a new phone at least once per year. The plan is called One Up, and while Sprint certainly hopes it has the upper hand on AT&T, Verizon, and T-Mobile, it actually works quite similarly to the competition.

If you sign up for One Up, the full off-contract price of your new phone is split up over 24 months. Over the first 23 months you'll pay the same amount — $24 for a Galaxy S4 — and then on the final month you'll pay the remainder of your balance ($47.99 in the case of the S4). However, you'll be able to upgrade your phone after 12 months and have the rest of the charges waived, so long as you sign up for another One Up agreement when you get a new device.

One Up is complicated just like the other early upgrade plans

For a "limited time" Sprint isn't charging any down payment when you get a new device using One Up, but once that deal ends, whatever you pay up front will apply towards the total cost of the smartphone. You will need to pay a $36 activation fee, however, and, like competing plans, you'll need to pay taxes on the entire unsubsidized cost of the device when you sign up.

In order to get One Up, you need to be on either Sprint's Unlimited, My Way plan (which costs $80 for unlimited calls, text, and data) or a My All-In plan (which comes in at $110 for unlimited talk, text, data, and 5GB of tethering). However, Sprint's offering $15 off either of those service plans per month if you sign up for One Up, making the Unlimited, My Way plan quite affordable at $65 per month. The discount will expire when you pay for your device in full.

You might save money if you upgrade every year

Like competing plans, you'll need to return your device to Sprint if you decide to upgrade before you've paid off the entire cost of your smartphone. Additionally, if you're a current customer you can sign up if you're at least 12 months into your contract — though Sprint will take your current device from you. There's no contract for One Up, but if you decide to cancel service you'll need to pay up the rest of your balance on your smartphone. Sprint is also including tablets as part of its One Up plans.

One Up is available starting today in Sprint stores. We'll have more on One Up soon, but beware because most of these early upgrade plans aren't a good deal.