Even with Huawei equipment fieled (which there isnt much left, Cricket and Clearwire were the largest incumbents for it, and those networks are gone) the BTS do

Even with Huawei equipment fieled (which there isnt much left, Cricket and Clearwire were the largest incumbents for it, and those networks are gone) the BTS does not have network access to phone home, they're walled off with very very very non-routable IP's (as in stuff used on the pubic internet) - there are too many layers of access control for what was being alleged to work in a practical sense.