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

# STIR/SHAKEN SIP Header Parameters

> Reference of STIR/SHAKEN SIP header parameters used by Telnyx — Identity, attest, origid, dest, and how to read and verify a signed identity header.

Telnyx provides call attestation information through the `verstat` parameter in the `P-Asserted-Identity` SIP header.

## Verstat parameter

```
P-Asserted-Identity: "John Doe" <sip:+18889809750@sip.telnyx.com;verstat=TN-Validation-Passed>
```

| Value                    | Description                                 |
| ------------------------ | ------------------------------------------- |
| `TN-Validation-Passed`   | Verification succeeded, A-level attestation |
| `TN-Validation-Passed-B` | Verification succeeded, B-level attestation |
| `TN-Validation-Passed-C` | Verification succeeded, C-level attestation |
| `TN-Validation-Failed`   | Verification failed (invalid certificate)   |
| `No-TN-Validation`       | No Identity header provided                 |

## Call scope

The `verstat` parameter is included for:

* Inbound calls from the PSTN
* On-net calls between Telnyx customers