Is there such a thing as negative data for cellphone companies or cell phones?
Only term that sounds familiar to that would be rollover-data (or getting credit for unused data from your allotment if you have one). Not all companies do that (most are just 'use it or lose it' kinda deal).
Not that I've ever heard, but what exactly do you mean by negative data? Do you mean you saw your data have dip negative or go down from earlier in the billing cycle?
how do I find out what carrier my phone is originally with?
My phone started wanting to use a GMail account when I tried to attach a picture to my text message.