Sprint in September followed the lead of T-Mobile, AT&T, and Verizon, announcing One Up, an early upgrade plan that lets customers trade in their phone every 12 months rather than two years. But just four months later, Sprint has quietly announced it is killing off the plan.

"Heads up! Sprint One Up was retired on Jan. 9, 2014," Sprint wrote in a note on its website. The company is now pushing customers to its new "framily" plan.

The now-defunct One Up plan let customers get a new device with no down payment and pay it off in monthly installments over the course of 24 months. After 12 consecutive payments, customers could then hand in their current device for a new one. As part of the plan, customers were entitled to a $15 per month service discount.

Those who purchased their device under the One Up program before Jan. 9 will still receive a $15 monthly service discount off Unlimited, My Way, and My All-in plans, Sprint said. The discount will be suspended after your next upgrade or if you change plans.

Meanwhile, Sprint's new Framily plan, unveiled at the Consumer Electronics Show last week, extends the concept of family plans to non-relatives. Customers can add up to 10 phone lines to one account to save money, with each person getting a separate bill. With the Framily plan, you can still upgrade early, but you'll first need to pay for unlimited data.

"We are always evaluating our programs and offerings to determine how best to meet the current needs of our customers," a Sprint spokesperson said in an email to PCMag. "We believe the new Sprint family plan offers our customers even greater value and even better options [than One Up] such as each family member having the ability to customize his or her own plan to meet their own individual needs."

The Framily plan starts at $55 per month for unlimited talk, text, and 1GB of data. That goes down by $5 per month for each person who joins, for a maximum monthly discount of $30 per line. Unlimited data, with the option for annual upgrades, is $20 per month per line.

Editor's Note: This story was updated at 1:35 p.m. with statement from Sprint.