Interesting. Kind odd that the MVNO would outperform the parent. Do you think there is any chance that its not the sim but the towers were just recently upgraded to 4G?
I remember reading somewhere that att sims do limit the type of signal you get. the mvno sims will not allow you to access lte, as I found out on an unlocked att lte phone.
so, I have to leave net 10 to go to the att go phone sim in order to get lte. I could get hspa+ with net 10.
for example, when I asked consumer cellular, they told me that their sims only allow you access to 3g, not hspa+ or lte.