I'm confused by the frequency band support for this phone. This website, and T-Mobile's website (https://support.t-mobile.com/community/phones-tablets-devices/android/zte-cymbal#id_1408981), claim it has has at minimum 3 GSM bands, but the manufacturer's spec sheet (http://zte-iqorsupport.custhelp.com/ci/fattach/get/1411/0/filename/Z320_Cymbal_Specification_Sheet_EN.pdf) lists only 2, which implies that it will not work outside North America. Which is correct?