> 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/telefonie/was-sind-codecs.md). # What are codecs? Audio codecs explained for sipgate – which codecs are supported and how they affect voice quality. To be able to transmit acoustic signals from a transmitter to a receiver, they must first be converted into data. This task is performed by a **Codec** handled by. A codec is a connected pair of algorithms that is responsible for the **encoding and decoding** of data. For larger amounts of data, a codec also ensures the **compression** and **decompression** of the data. Codecs play an important role in VoIP telephony, as they control the quality of the connection here. Compressing codecs can be divided into two groups: lossy and lossless codecs. **Lossy codecs** can achieve greater compression of the data packets and therefore require less bandwidth during transmission. However, this negatively affects the quality. **Lossless codecs** transmit the data packets without compression and therefore without loss of quality, but require more bandwidth. #### **Which codecs are supported by sipgate?** * G.722 (approx. 100 Kbit/s) * OPUS (approx. 40 Kbit/s) * G.711a (approx. 100 Kbit/s) * G.711u (approx. 100 Kbit/s) * GSM (approx. 20 kbit/s) *** * **Which RTP / voice codecs does sipgate use?** * G.711: approximately 100 kbit/s * GSM: 13 - 20 kbit/s * G.722/ HD *** #### **Which codec does** [**satellite**](https://www.satellite.me/) **and** [**sipgate App**](https://clinq.com/)**?** * Opus: 6 kbit/s - 510 kbit/s *** #### **How much data is used in approx. ten minutes?** * VoIP call via G.711 / 10 min. approximately 7.5 MB * VoIP call via GSM / 10 min. approximately 1.5 MB *** #### **Are data channels ISDN (X.75) or analog X.25 supported?** No, not planned at the moment. --- # 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/telefonie/was-sind-codecs.md?ask=&goal= ``` `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.