When you're getting beaten down by your larger and smaller rivals, it's time for desperate measures. And there's certainly a hint of that with Sprint's latest offer for AT&T and Verizon customers: Switch over to Sprint starting on December 5 and your cellphone bill will get cut in half. The carrier will also cover early termination fees at up to $350 per line (something it started doing earlier this year). This isn't just a temporary discount -- Sprint says you'll keep the lower price as long as you stick with your plan. But of course, there's a bit of a catch. You'll have to lease your new Sprint phone or buy it outright, you won't be able to take advantage of contracted pricing. You also better make sure you love your plan, as any future upgrades will nuke the discount. You can count this generous offer as yet another "bold action" by Sprint's new CEO Marcelo Claure, who laid off 2,000 employees last month in an attempt to revitalize the ailing carrier.