Just found this new app, it's called , basically mobile carriers have been found attaching tracking IDs in the form of (X-ACR or X-UIDH) through your http:// address bar everytime you run a search, while connected to mobile/cellular data (non-wifi.) The personal information being tracked relates to your phone number and IMEI, which this is a practice that has been known about for some time, however, doesn’t seem to be that easy to opt out of it.
I’ve already discovered AT&T using UIDH tracker and have opted out through the link provided below, however, AT&T is still ignoring the opt out. VPN is blocking it after this screenshot below.
For more information on how to opt out of tracker checking known from AT&T, Verizon, Sprint, Bell Canada & Vodacom Unique Identifier beacons check out