From WIRED: http://www.wired.com/2014/10/verizons-perma-cookie/
QuoteAccording to Verizon spokeswoman Debra Lewis, there's no way to turn it off. She says that Verizon doesn't use the UIDH to create customer profiles, and if you opt out of the company's Relevant Mobile Advertising program (you can do this by logging into your Verizon account here), then Verizon and its advertising partners won't be using it to create targeted ads. But that's beside the point, says Hoffman-Andrews. Because Verizon is broadcasting this unique identifier to every website, ad networks could start using it to build a profile of your web activity, even without your consent.
The fact that the UIDH was around for two years before getting any serious attention is a testament to the murky and challenging nature of privacy on today's internet. Verizon has made no secret of its ambitions to cash in on the mobile advertising market. But the technical details of how it is doing this have been hard to uncover.
'IT'S GONE RELATIVELY UNREMARKED BY THE SECURITY, PRIVACY, AND BROADER TECHNICAL COMMUNITY, IN PART, BECAUSE IT'S SO HARD TO OBSERVE.'
You can test to see if your mobile device is broadcasting a UIDH on this website (http://lessonslearned.org/sniff), run by Kenneth White, a security researcher. (Go to the site, and if there is nothing displayed after the line "your UID is reporting," then you are not displaying a UIDH.) White says that the majority of Verizon Wireless customers who test their devices on his site display the perma-cookie. But not everyone does.
AT&T is reportedly considering wide scale deployment of a similar system it has been testing which you can opt out of.
The cookie-display website, in case it doesn't show in the quote, is http://lessonslearned.org/sniff
Here is the AT&T Opt Out page which you need to access while on 3g/4g
not while on WiFi. http://205.234.28.93/mobileoptout/