Hoping someone has some insight. I purchased 3 Lumia 640s and got them unlocked from ATT. I purchased and activated sims from Walmart Family Mobile. It uses T-Mobile as a carrier. I can receive calls and texts but I have been unable to get the mobile data to work. I've tried all the listed APN info, to no effect. I've contacted C/S at Walmart Family Mobile and they have no answer. I am at my wits end. I've attempted every APN setting possible in both 8.1 and now 10. Does anyone have any clue what I have going on? I've seen several people on here that have the same phone and carrier....hopefully someone has some insight. Thanks in advance.