> ## Documentation Index
> Fetch the complete documentation index at: https://docs.interchange.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Set default advertiser

> Set the catch-all GAM advertiser for buyer routing on an ESA

`PUT /api/v2/storefront/esa/{esaId}/gam/default-advertiser`

Sets the default Google Ad Manager advertiser for a GAM-backed embedded sales agent. Every incoming buyer that has no matching per-buyer mapping routes to this advertiser. Setting it clears the `Default GAM advertiser` setup blocker. Call again with a different `gamAdvertiserId` to replace it.

## Request

<CodeGroup>
  ```bash curl theme={null}
  curl -X PUT https://api.interchange.io/api/v2/storefront/esa/123/gam/default-advertiser \
    -H "Authorization: Bearer $SCOPE3_API_KEY" \
    -H "Content-Type: application/json" \
    -d '{ "gamAdvertiserId": "4567890123" }'
  ```
</CodeGroup>

## Parameters

| Field             | Type    | Required | Notes                                                                                                                                                        |
| ----------------- | ------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `esaId`           | integer | Yes      | Path. Embedded sales-agent connection id                                                                                                                     |
| `gamAdvertiserId` | string  | Yes      | GAM advertiser id from [list](/v2/storefront/buyer-routing/tasks/list-gam-advertisers) or [ensure](/v2/storefront/buyer-routing/tasks/ensure-gam-advertiser) |

## Response

```json theme={null}
{
  "defaultGamAdvertiserId": "4567890123"
}
```

`defaultGamAdvertiserId` echoes the advertiser now serving as the catch-all for unmatched buyers.

## Errors

* `400 VALIDATION_ERROR` — `gamAdvertiserId` is empty, `esaId` is not a positive integer, or the ESA is not Google Ad Manager-backed.

See [Errors](/v2/reference/errors) for the full error contract.

## Related

<CardGroup cols={2}>
  <Card title="Buyer routing tasks" href="/v2/storefront/buyer-routing/tasks" icon="list-check">
    All buyer-routing operations
  </Card>

  <Card title="Buyer routing overview" href="/v2/storefront/buyer-routing/overview" icon="route">
    How buyers resolve to advertisers
  </Card>

  <Card title="Ensure GAM advertiser" href="/v2/storefront/buyer-routing/tasks/ensure-gam-advertiser" icon="plus">
    Provision a catch-all advertiser
  </Card>

  <Card title="Create buyer mapping" href="/v2/storefront/buyer-routing/tasks/create-buyer-mapping" icon="link">
    Override the default for one buyer
  </Card>
</CardGroup>