T-Mobile undercuts competition with $5-per-month iPhone upgrade plan

Desperate for a new iPhone but have no money to spare? T-Mobile’s got you covered with an iPhone 6s plan that will only cost you $5 a month, or $9 for the larger 6s Plus, if you trade in your current phone.T-Mobile’s Jump On Demand plan lets you upgrade your phone three times per year for a monthly hardware fee on top of your regular cell phone plan. The carrier had a similar promotion for the last-generation iPhones, but prices started at $15 a month. Sprint’s iPhone upgrade p