There’s a huge caveat in T-Mobile’s new $40 plan that you need to k**w about T-Mobile on Wednesday made its next big move to shake up the wireless world by an**uncing a new cheap $40 wireless*plan that offered unlimited voice and text along with 500MB of LTE data per month. The big selling point of this new plan is that, unlike Verizon and AT&T, T-Mobile won't charge you any data overage fees if you go over your monthly allotment. However, there's a big asterisk here that anyone who's interested in subscribing to the plan should k**w about before taking the plunge.