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

# Fonial SIP trunk

> Connect a Fonial number with a SIP user for outbound and SIP-URI forwarding for inbound

<Warning>
  Voice-AI SIP trunking is available only on Fonial's paid **PLUS** plan. On the **FREE** tier, ask Fonial support (0221 66966966, [support@fonial.de](mailto:support@fonial.de)) whether your account can be upgraded before starting this setup.
</Warning>

There is no dedicated Fonial import. Connect a Fonial number the same way as any other provider, through **Numbers → Add SIP integration** — but Fonial's setup splits across two separate mechanisms rather than one shared trunk:

* **Outbound** — a Fonial **SIP user** supplies the credentials the platform authenticates with.
* **Inbound** — a Fonial **destination (Ziel) forwarding to a SIP URI** sends calls to the platform's SIP address.

```mermaid theme={null}
sequenceDiagram
    participant Caller
    participant Fonial
    participant Platform
    participant Assistant

    Note over Fonial,Platform: Inbound — forwarding to SIP URI
    Caller->>Fonial: Call to your Fonial number
    Fonial->>Platform: Forward to "Our SIP address"
    Platform->>Assistant: Route to the assigned assistant
    Assistant->>Platform: Real-time voice response
    Platform->>Caller: Conversation with the assistant
    Note over Platform,Fonial: Outbound — SIP user auth against sip.plusnet.de
```

<Note>
  The Fonial SIP user stays **Offline** in Fonial's dashboard permanently — that's expected, not a fault. The platform never sends a SIP REGISTER; inbound calls arrive through the forwarding destination, not through registration.
</Note>

## Set it up

### 1. Create a SIP user in Fonial

In the Fonial customer portal ([kundenkonto.fonial.de](https://kundenkonto.fonial.de)), open **SIP-Benutzer** and create a new SIP user (any name, e.g. `Famulor`). It appears in the list with status **Offline** — leave it that way.

### 2. Open its credentials and assign the number

Open the new SIP user's credentials to get its **username**, **password**, and **server URL** (`sip.plusnet.de`). Then, under **Rufnummern**, select the number to connect and assign it to that SIP user.

### 3. Create the platform SIP trunk

In **Numbers → Add SIP integration**, use these settings:

| Field                          | Value                                             |
| ------------------------------ | ------------------------------------------------- |
| Trunk type                     | **SIP Extension** — not Phone number (DID)        |
| Your SIP extension             | The Fonial number in E.164 (e.g. `+498956546546`) |
| Username / Password            | The Fonial SIP user's credentials (step 2)        |
| SIP address (outbound)         | `sip.plusnet.de`, no port                         |
| Outbound calling number format | International with `+`                            |
| Country                        | Germany (DE)                                      |

Copy **Our SIP address** shown under inbound settings (e.g. `xxxxxx.eu.sip.livekit.cloud`) — you need it next.

### 4. Forward the number to the platform (inbound)

Build the SIP URI from the Fonial number **without** the leading `+` and the address copied in step 3:

```text theme={null}
sip:<Fonial number without +>@<Our SIP address>
```

Example: `+498956546546` and `xxxxxx.eu.sip.livekit.cloud` become `sip:498956546546@xxxxxx.eu.sip.livekit.cloud`.

In Fonial, go to **Telefonanlage → Ziele → Neues Ziel anlegen**, choose **Weiterleitung (Mobilfunk, Festnetz, Fax oder SIP-URI)** as the destination type, name it, select **Weiterleitung auf SIP-URI**, paste the SIP URI above, set the outgoing number to the Fonial number you're connecting, and save.

### 5. Assign an assistant and test

Assign the connected number to an assistant, then call it externally to confirm the assistant answers.

## Common issues

<AccordionGroup>
  <Accordion title="SIP user shows Offline">
    Expected — see the note above. The platform never registers; inbound calls use the SIP-URI forwarding from step 4, not registration.
  </Accordion>

  <Accordion title="Inbound calls don't arrive">
    Check the SIP-URI forwarding (step 4): correct number format (no `+`), the exact **Our SIP address** copied from the platform (no extra `sip:`, no whitespace), and the right outgoing number selected on the Fonial destination.
  </Accordion>

  <Accordion title="Outbound calls fail">
    Recheck username, password, and `sip.plusnet.de` from the Fonial SIP-user credentials (step 2), and confirm the outbound calling number format is set to international with `+`.
  </Accordion>
</AccordionGroup>

## Validate the setup

Call the connected number from an external phone and confirm a new inbound record in **History**, the assigned assistant, and two-way audio. Then place one outbound test call to confirm the SIP-user credentials independently.

Sources: [Fonial trunking setup](https://www.fonial.de/hilfe/trunking/einrichtung-trunking). Accessed 22 August 2026.