> For the complete documentation index, see [llms.txt](https://docs.helodata.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.helodata.com/products/overview-1/asn-targeting.md).

# ASN targeting

For mobile workloads, ASN targeting is the **single most important parameter**. Many sites detect "this user is on cellular *and* on carrier X" — pinning the carrier is what turns a generic mobile IP into a trusted one.

## How to specify

Same syntax as residential:

```
helo_s1a2b3c4d5e-type-mob-region-us-asn-6167
```

ASN is a decimal integer, no `AS` prefix.

## Carrier ASN reference (top markets)

| Country | Carrier                       | ASN    |
| ------- | ----------------------------- | ------ |
| US      | Verizon Wireless              | 6167   |
| US      | T-Mobile US                   | 21928  |
| US      | AT\&T Mobility                | 20057  |
| GB      | EE                            | 12576  |
| GB      | Vodafone UK                   | 12969  |
| GB      | Three UK                      | 60339  |
| DE      | Deutsche Telekom (Telekom DE) | 3320   |
| DE      | Vodafone DE                   | 3209   |
| DE      | Telefónica O2 DE              | 6805   |
| FR      | Orange                        | 3215   |
| FR      | SFR                           | 15557  |
| FR      | Bouygues Telecom              | 5410   |
| JP      | KDDI                          | 2516   |
| JP      | NTT Docomo                    | 9605   |
| JP      | SoftBank                      | 17676  |
| KR      | SK Telecom                    | 9318   |
| KR      | KT                            | 4766   |
| KR      | LG U+                         | 17858  |
| BR      | Vivo / Telefónica BR          | 26599  |
| BR      | TIM                           | 26615  |
| BR      | Claro                         | 28573  |
| IN      | Reliance Jio                  | 55836  |
| IN      | Bharti Airtel                 | 24560  |
| IN      | Vodafone Idea                 | 38266  |
| MX      | Telcel                        | 8151   |
| MX      | AT\&T MX                      | 32098  |
| CA      | Bell Mobility                 | 577    |
| CA      | Rogers                        | 812    |
| CA      | Telus                         | 6327   |
| AU      | Telstra                       | 1221   |
| AU      | Optus                         | 4804   |
| AU      | TPG / Vodafone AU             | 133612 |

For the complete live list per country, query:

```bash
curl -H "Authorization: Bearer API_KEY" \
     "https://api.helodata.com/v1/mobile/asns?region=us"
```

## Combining with other parameters

```
helo_s1a2b3c4d5e-type-mob-region-us-asn-6167                              # US, Verizon
helo_s1a2b3c4d5e-type-mob-region-us-state-ca-asn-6167                     # California Verizon
helo_s1a2b3c4d5e-type-mob-region-us-asn-6167-session-x-sesstime-60        # Sticky Verizon session
```

`state` and `city` on top of `asn` often produce insufficient pool — see [Locations](/products/overview-1/locations.md).

## When to use ASN

For mobile, **almost always**. Specifically:

* Apps that show different content based on detected carrier
* Sites that bind anti-bot fingerprints to ASN
* A/B testing carrier-specific features
* Compliance testing (ensure feature works on all carriers in a market)

## When **not** to use ASN

Only when you genuinely need carrier diversity — e.g. measuring how a site behaves across all carriers in a country. Even then, prefer rotating the ASN per request rather than leaving it empty, so you can attribute results.

## Inspecting the chosen ASN

```
X-Helodata-Exit-ASN: 6167
X-Helodata-Exit-ASN-Name: Cellco Partnership d/b/a Verizon Wireless
```

The name field follows the operator's BGP registration — useful for log analysis when you don't memorize ASN-to-carrier mappings.


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