The next phase in T-Mobile’s “uncarrier” strategy looks set to come down the pipeline on January 9 at the Consumer Electronics Show in Las Vegas. Invitations sent to media members on Friday failed to outline exactly what we might see at the press conference but there are already some pretty solid rumors making the rounds.

According to a couple of unnamed sources as reported by TmoNews, Uncarrier 4.0 (codenamed “Houdini”) will consist of an Early Termination Fee (ETF) promotion in which the wireless carrier will essentially pay off your ETF with your current carrier if you switch to T-Mobile.

Customers will be eligible for up to $350 in total credit when switching. They will earn instant credit by trading in their existing handset and will be credited the ETF fee when they submit the final bill to T-Mobile. As such, new customers must trade in their old device and purchase a new phone through T-Mobile to qualify.

We are told the focus here is on families switching up to five lines regardless of contract end dates although I see no indication where it wouldn’t also work for individual lines. According to documentation seen by the publication, the program will launch on January 15.

We’ve seen other carriers offer similar limited-time promotions in the past but nothing that is permanent. If true, I imagine such a promotion could once again shake up the industry and more than likely force other carriers to follow suit but at this time, keep in mind that it is little more than a rumor.