# Changes to default 3CX Headers

In order for the 3CX PBX to function correctly with outbound calls when using the Hosted Network PAYG or Unlimited SIP Trunks you need to modify the default outbound parameters on the trunk.

If you experience issues with calls being rejected by the VoIPNow server or getting service unavailable messages please modify the below settings in the Outbound Parameters of the trunk:

| SIP Field           | Variable                                |
| ------------------- | --------------------------------------- |
| Contact : User Part | "AuthID" Authentication                 |
| From : User Part    | "AuthID" Authentication                 |
| From : Host Part    | "GWHostPort" gateway/provider host/port |

Changing the above settings should then allow calls to flow through the platform successfully.

If you still encounter issues with the calls please contact our support team via email at <support@hostednetwork.com.au> or via phone at 1300-781-148


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://kb.hostednetwork.com.au/support/services/voice-over-ip-voip/general/3cx-guides/changes-to-default-3cx-headers.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.