> For the complete documentation index, see [llms.txt](https://help.sipgate.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.sipgate.de/cloud-telefonanlage/en/using-sipgate/mobilfunk/was-ist-der-mobile-zusatzanschluss.md).

# What is the mobile extension line?

There are situations where it is enough to equip individual people or even devices with mobile service, without having to book or create them as new users in the phone system. This is possible with the feature **mobile additional connection** possible.

This allows you, for example, to provide employees who want to be reachable on the go and can make calls and use mobile data. Alternatively, devices such as surveillance cameras, alarm systems, and card readers can be conveniently equipped with mobile service via the mobile additional connection. Several employees can then access them independently of one another.

With the mobile additional connection, unlike with newly created users, **not** the full range of the sipgate phone system can be used. For example, **no voicemail or event list** available.

## Where can I find the feature?

The starting point for user-independent mobile service is the [**mobile service tile**](https://app.sipgate.com/mobile-telephony) in the **account management**. Here you click on **book mobile options**.

![sipgate-Hilfecenter-Mobilfunk3.png](/files/9ed1d1db74d099141ef699bb1495518a5427b9f5)\
Then in the next step you select **mobile additional connection**.

After you have assigned the **device name** , you add a phone number.

{% hint style="warning" %}
**Important:** Please note that for this feature you can **only use mobile numbers** . Landline numbers are not available for this feature.
{% endhint %}

If your **Sender number** is to be the same as the previously added phone number, you must enter it in the **device settings** of the corresponding **device card** manually.

![sipgate-help-center-mobile-service5.png](/files/4622fe472ef696d5c7c8bfd167d110593b3e912e)


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## 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, and the optional `goal` query parameter:

```
GET https://help.sipgate.de/cloud-telefonanlage/en/using-sipgate/mobilfunk/was-ist-der-mobile-zusatzanschluss.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

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.