T-Mobile is planning a big announcement at CES in Las Vegas later on today, but thanks to a leaked ad that’s been making its way around the web this morning, we already know what it has up its sleeve. As part of its Un-carrier 4.0 scheme, T-Mobile will pay your whole family’s early termination fees if they switch carriers and trade in their old smartphone.

AT&T kicked off a similar promotion last week when it announced it would give T-Mobile customers up to $450 per line if they switched and traded in their old smartphone. Now T-Mobile’s set to counter that with Un-carrier 4.0, which is kind of ironic when you consider that T-Mobile CEO John Legere called AT&T’s promotion “desperate.”

Not a lot of detail is included in the ad, unfortunately, but you’ll notice the fine print mentions a qualifying service and device purchase with port-in from AT&T, Verizon, or Sprint is required. So T-Mobile will pay your early termination fees as long as you trade in your old device, then take out a new contract and purchase a new device.

The ad also states that a maximum of five lines can be ported over, which is a shame if you have six family members hoping to make the switch.

T-Mobile will be hoping that the new scheme encourages consumers to switch to one of its new Un-carrier plans sooner rather than later. We’ll find out more about it when T-Mobile makes it official; its even kicks off at 12:30 p.m. Pacific.

• SourceDroid-Life