I haven't had the opportunity to tinker with this, but what if the client sends a X-UIDH: header of it's own? Will VZW overwrite the header, or will it pass it through? If it doesn't clobber it, there's a browser plugin waiting to be written.
As I understand it, they offer an "opt out" that doesn't actually opt you out of this.
Truly gross behavior, though.
And where would you go? AT&T? Is that really a better option?
Sprint and TMo just don't have the reception everywhere I go (or didn't last time I checked).
Or at least, some plans do. My legacy per minute plan does.
I'm pretty sure Sprint roams on Verizon, they just won't offer you service for an address where you would be roaming all the time.
That included the middle of the Appalachian mountains.
Better still have the plugin get a group of known headers and distribute them all over.