Twitter's MoPub is using the UIDH “perma-cookies” inserted by Verizon into web pages
Somebody's Already Using Verizon's ID to Track Users — Twitter's mobile advertising arm enables its clients to use a hidden, undeletable tracking number created by Verizon to track user behavior on smartphones and tablets.
Context & Ripple Effects
Days after Wired revealed that Verizon was inserting an undeletable unique identifier into web traffic with no opt-out, ProPublica has found the first confirmed commercial consumer of that header: MoPub, the mobile ad exchange Twitter bought in 2013. What had been a network-engineering curiosity is now a live targeting mechanism inside one of the largest mobile ad platforms.
The timing matters because Verizon has been building this pipeline for years — from early reports of mobile Web monitoring back in 2011 through its 2014 move to pass desktop browsing habits to mobile advertisers. The MoPub disclosure shows the demand side arriving before any public policy debate about the supply.
First-order effects
- MoPub's ad clients can now track and target Verizon smartphone and tablet users via the UIDH header that those users cannot delete or block, effectively converting every page request into a persistent identity beacon.
- Verizon subscribers become trackable across apps and sites without consent, while MoPub gains a targeting signal that survives the cookie-clearing defenses its inventory would otherwise honor.
Second-order effects
- Other ad intermediaries face pressure to adopt the same free, undeletable identifier rather than lose match rates to rivals — a dynamic that materialized when Verizon partner Turn began using UIDH to resurrect deleted cookies months later.
- Privacy researchers and press now have a concrete named abuser to organize around, shifting the story from abstract traffic alteration to specific platforms monetizing it.
Third-order effects
- If carriers sit at the chokepoint of all mobile traffic, network-inserted identifiers threaten to make user-side privacy controls like cookie deletion structurally irrelevant, inviting regulator and FTC scrutiny of carrier-level tracking.
- The pattern points toward carriers consolidating advertising power by fusing network access with ad data — a path that culminated when Verizon merged its supercookie apparatus into AOL's ad network, matching online habits with subscriber identities.
The trend: Carriers are leveraging their position as unavoidable traffic middlemen to build persistent advertising identifiers, turning network infrastructure itself into the tracking layer that browser-based privacy controls cannot reach.