I have an LG Optimus 2x (G2X) and T-Mobile unlimited data. I sometimes use the wifi hotspot when I'm using my computer and there is no wifi available. T-mobile charges 14.99 for this service\month, but I use it alot and I'm never charged. Do they know I'm using it, or not? Is there some threshold I must meet before they start charging me? Are there apps that I can use so TMO won't know I'm using it? TEACH ME! Thank you.