AT&T must really be getting sick of T-Mobile's disruptive "Un-carrier" shenanigans.

It's trying to lure T-Mobile customers away with a pair of incentives worth up to $450 ... if certain conditions are met, that is.

Beginning today, T-Mo members who switch to AT&T can earn a $200 credit per line if they also sign up for Next, the carrier's early upgrade program, buy a full-price device, or activate a device they already own.

There are some qualifiers in the fine print: Customers will need to sign up for an AT&T Mobile Share Value plan, and the credit is not available if they sign a two-year contract.

A very merry uncarrier to you

In addition, T-Mobile customers who switch to AT&T and trade in their existing phones will receive a promotion card for up to $250 that can be used on AT&T products and services.

Not all phones will earn that much, but AT&T's announcement noted it includes the "latest and most popular" ones will.

Those interested can learn more at www.att.com/switchfromtmo.

T-Mobile has spent the last year or so initiating risky changes, like unlimited international data and texts, to differentiate itself from the competition - and it seems to be working.

In December T-Mobile teased that it will soon make another "uncarrier" announcement, so expect something big and beautiful at CES next week.

Update: Aaand T-Mobile has a response to AT&T newest offer.

"This is a desperate move by AT&T on the heels of what must have been a terrible Q4 and holiday for them," T-Mobile CEO John Legere wrote in a statement posted on the carrier's website.

"I'm flattered that we have made them so uncomfortable! We used AT&T's cash to build a far superior network and added Un-carrier moves to take tons of their customers - and now they want to bribe them back! Consumers won't be fooled ... nothing has changed; customers will still feel the same old pain that AT&T is famous for. Just wait until CES to hear what pain points we are eliminating next. The competition is going to be toast!"

Seems it's really game on from here on out.