The short answer
No billboard can push an ad to your phone. What exists is less dramatic and more common: some outdoor advertising companies buy location data collected by apps on people's phones, estimate which devices passed a particular board, and later show those devices ordinary online ads. The billboard never talks to the phone. The link is made afterwards, in a database.
For advertisers, this is a legitimate measurement and targeting tool when the data is properly consented and aggregated. It is also a privacy question your brand is attached to, so it is worth knowing what you are buying.
What happened in Santa Monica
In late August 2026, the first digital billboards in Santa Monica in nearly 40 years went up above the Third Street Promenade, under a digital display district the city council adopted in December 2025. The programme allows up to 16 screens, and residents have argued about brightness and the character of the downtown.
In September a clip went viral on X claiming the new screens could connect to passing phones and push advertisements to them. The operator, Orange Barrel Media, told local press that the Santa Monica signs contain no technology that detects, tracks, communicates with or engages with smartphones, and that seeing an ad on them cannot be used to target that person's phone later. The claim appears to have confused the screens with a mobile retargeting product sold by a different outdoor company.
The confusion is understandable. The product is real. It just does not work the way the clip described.
How OOH mobile retargeting actually works
The process has four steps, none of which involve the billboard itself.
- Collection. Many apps collect location data, sometimes for their own features and sometimes to sell. It flows to data companies through software development kits and ad exchanges, with whatever consent the app obtained.
- Exposure inference. The outdoor company draws an area around each board, taking into account the direction it faces and where it can be seen from. Devices whose location records fall inside that area, at a time the ad was showing, are counted as probably exposed.
- Activation. Those devices, identified by advertising IDs rather than names, are packaged into an audience that can be targeted with display or video ads in other apps.
- Attribution. The same data is used to compare exposed devices with similar unexposed ones: did more of them visit the store, download the app or visit the website?
Clear Channel Outdoor, for example, describes its RADARConnect product as using aggregated and anonymous mobile location data to identify exposure to a board and later serve a mobile or digital ad, and says it licenses such data from partners rather than collecting personal information itself.
Myth and reality
| Claim | Reality |
|---|---|
| The billboard sends ads to your phone | No. Any follow-up ad arrives later through normal ad networks, if at all. |
| The billboard connects over Bluetooth or Wi-Fi | Not for retargeting. Proximity messaging via beacons requires an app you installed and permissions you granted. |
| They know who you are | They work with device advertising IDs and location records. Those are designed to be pseudonymous, but location histories can be re-identified, which is why regulators treat them seriously. |
| Some screens have cameras | Some audience-measurement systems use cameras to count viewers or estimate attention. Whether a particular screen has one is a question for its operator. |
| You cannot opt out | You can limit it by restricting app location permissions and resetting or disabling your phone's advertising ID. |
The privacy rules that apply
Location data is the part regulators care about. In the US, the FTC took action in 2024 against data brokers including X-Mode and InMarket over the collection and sale of location data, including data revealing visits to sensitive places. California's privacy law treats precise geolocation as sensitive personal information. In Europe, GDPR applies to location data linked to a device. In India, the Digital Personal Data Protection Act requires a lawful basis, usually consent, for processing personal data, with its operational rules phasing in from November 2026, as we covered in the DPDP consent deadline.
None of this makes OOH retargeting illegal. It makes the data's origin your problem if it turns out to have been collected badly.
What to ask before you buy location-based OOH
- Where does the data come from? Which kinds of apps, and what consent did users give?
- How is exposure defined? A radius around the board, or an area based on what can actually be seen?
- What are the aggregation thresholds? Are results reported only for groups large enough to prevent identifying individuals?
- Are sensitive locations excluded? Clinics, places of worship, shelters and similar sites should be excluded from targeting and reporting.
- Is there a control group? Attribution without a comparison of similar unexposed devices tells you very little.
- What happens to the audience afterwards? Is it deleted after the campaign, or kept and combined with other data?
A vendor who answers these clearly is probably running a careful product. One who cannot is a risk you take on with your brand name attached.
Measuring billboards without tracking anyone
Most businesses do not need device-level data to know whether outdoor worked. Lift measurement is cheaper and uncontroversial:
- Branded search in the board's area, from Search Console and Google Trends.
- Direct and local website sessions in GA4, compared with a baseline.
- Enquiries and walk-ins, with every new customer asked where they heard of you.
- A short board-only URL or code.
- A matched comparison area with no boards.
We explain how to set this up, with rates for Indian cities, in billboard advertising costs in India. And whatever the board leads people to, the landing page should expect them: people who search your name after seeing a board judge you on the first screen of your site. If yours is not ready for that, we can help.