# ASN targeting

ASN (Autonomous System Number) targeting lets you pin an exit IP to a specific ISP — useful when a target site treats certain carriers differently, or when you want IPs that share a network reputation.

## How to specify

Append `-asn-{number}` to the username. The ASN is a decimal integer with no `AS` prefix.

```
helo_s1a2b3c4d5e-type-res-region-us-asn-7922
```

Common US residential ASNs:

| ASN   | ISP                |
| ----- | ------------------ |
| 7922  | Comcast            |
| 22773 | Cox                |
| 7018  | AT\&T              |
| 11427 | Charter / Spectrum |
| 20115 | Verizon            |
| 209   | CenturyLink        |

For other countries, look up the carrier on a public registry like bgp.tools or query our location API:

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

## Combining with other parameters

ASN narrows the pool **after** country/state/city filtering. Compatible combinations:

```
helo_s1a2b3c4d5e-type-res-region-us-asn-7922                          # US, Comcast
helo_s1a2b3c4d5e-type-res-region-us-state-ca-asn-7922                 # California Comcast only
helo_s1a2b3c4d5e-type-res-region-us-state-ca-city-la-asn-7922         # LA-area Comcast
helo_s1a2b3c4d5e-type-res-region-us-asn-7922-session-x-sesstime-15    # Sticky Comcast session
```

If the combined filter produces fewer than 10 live IPs, the gateway returns a `522` with response header `X-Helodata-Insufficient-Pool: true` rather than fall back silently. Loosen the filter (drop `city`, then `state`, then `asn`) to find a viable combination.

## When to use ASN targeting

* **Carrier-locked content** — services that geo-restrict by ISP (some streaming, banking, telco portals)
* **Detection bypass** — sites that score carrier diversity as a bot signal
* **Reproducibility** — pinning the same carrier across a long-running test
* **Quality control** — some residential pools are higher-quality on premium carriers

## When **not** to use ASN

* General scraping where carrier diversity is a *feature*, not a bug — leave ASN unset
* Very small markets — even tier-1 ASNs may have <100 live IPs at a moment
* Combined with `city` in non-tier-1 countries — almost always insufficient pool

## Inspecting the chosen ASN

The gateway echoes the exit IP's ASN back in a response header:

```
X-Helodata-Exit-ASN: 7922
X-Helodata-Exit-ASN-Name: Comcast Cable Communications, LLC
```

Use this to verify your targeting and to debug `IP location mismatch` errors when the ASN's geo doesn't match the city you requested.

## Mobile vs residential ASNs

ASNs in the residential pool belong to fixed-line ISPs. For mobile carrier ASNs (Verizon Wireless, KDDI, Vodafone…), use the [Mobile proxies](/products/overview-1/asn-targeting.md) `type-mob` product.


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