## Set SMS language
It's possible to specify the content language for SMS verification. The desired language is set in the initiate verification request 'Accept-Language' header. Setting this header is optional. If not included the application's default SMS content language is used, which by default is en-US. If an SMS template for the desired language is not found it's defaulted to 'en-US' unless a different default language has been defined for the requesting application.
More information on the 'Accept-Language' header can be found from [IETF](https://tools.ietf.org/html/rfc3282) and the [HTTP/1.1 documentation](https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4).
The content language specified in the API request or in the callback can be overridden by carrier provider specific templates, due to compliance and legal requirements, such as [US shortcode requirements](https://community.sinch.com/t5/SMS/Sinch-US-Short-Code-Onboarding-Overview/ta-p/7085).
*Example* - SMS verification specifying content language

```html
Headers: ... Accept-Language: es-ES ... [POST]
https://verification.api.sinch.com/verification/v1/verifications
```

```json
{
  "identity": { "type": "number", "endpoint": "+46700000001" },
  "method": "sms"
}
```
The actual language that was selected is returned in the `Content-Language` HTTP content header. As outlined above, this may differ from the requested language due to either that language not having SMS content defined, or it being overridden by provider requirements.
*Example* - SMS verification response with selected content language