While carriers generally seem to care only about boosting their subscriber numbers nowadays by making it as easy and as cheap as possible to switch from a different mobile network operator, T-Mobile likes to frequently swim against the tide with cool discounts and freebies for both new and existing customers.
In a nutshell, Magenta will give (almost) everyone a free voice line with no strings attached or hoops to jump through. All you need is to already have two paid lines of wireless service on a “qualifying rate plan” or be willing to activate them now in order to get a third one at no extra cost.
Before doing your pre-holiday celebration dance, you may also want to keep in mind not all plans and existing customers will actually be eligible for this crazy “holideal”, although the full list of exclusions and exceptions is not yet available.