According to several reports, Verizon Wireless has introduced a persistent, hidden tracking mechanism into mobile applications and browsers, which third parties could exploit for the purpose of tracking the web activity of Verizon's subscribers. Allegedly, Verizon subtly alters the web traffic of its wireless subscribers by inserting a unique identifier (customer ID tag) into the data flowing between its mobile subscribers and the websites they visit, thereby enabling collection of information concerning web activity.
 
This tracking mechanism, which has been dubbed as a "Super-cookie", has raised considerable privacy concerns, as it persists even if a user clears its cache, enters private browsing mode or opts out of the program, thereby subjecting Verizon's subscribers to covert online tracking by third parties.
 
Recently, following an appeal from the Senate Committee on Commerce, Science and Transportation, which questioned Verizon's use of the unique identifier, Verizon announced it would allow subscribers to opt out of the insertion of the tracking mechanism.