Mexico is becoming a hotbed of operator competition, with AT&T’s expansion there, America Movil’s fightback, and a growth in cross-border roaming services with the US. T-Mobile USA recently removed any roaming fees for customers travelling to Mexico (or Canada). This was part of its latest ‘Uncarrier’ tactics, designed to shake up the way customers pay for mobile services and devices in order to disrupt the big three operators. ‘Uncarrier Amped’ includes changes to the Jump device upgrade program as well as the roaming amnesty. Its ‘Mobile Without Borders’ announcement was clearly targeted at AT&T, which has used its $4.4bn acquisitions of Nextel Mexico and Iusacell to announce a range of cross-border services and point towards a fully harmonized US/Mexican zone…