> For the complete documentation index, see [llms.txt](https://teamhelp.sipgate.co.uk/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://teamhelp.sipgate.co.uk/use-sipgate/telephony/what-are-codecs.md). # What are codecs? In order to transmit acoustic signals from a transmitter to a receiver, they must first be converted into data. This task is performed by a codec. A codec is a coherent pair of algorithms that is responsible for encoding and decoding data. For larger amounts of data, a codec is also responsible for compressing and decompressing the data. Codecs play an important role in VOIP telephony, as they control the quality of the connection. Compressing codecs can be divided into two groups, lossy and lossless codecs. Lossy codecs can achieve higher compression of the data packets and therefore require less bandwidth during transmission. However, this has a negative impact on quality. Lossless codecs transmit the data packets without compression and therefore without loss of quality, but require a higher bandwidth. #### Which codecs are supported with sipgate? * G.711a (sipgate VoIP/SIM/trunking) * G.711u (sipgate VoIP/SIM/trunking) * GSM (sipgate VoIP/SIM/trunking) * G.722 (sipgate VoIP/SIM/trunking) * OPUS (satellite and sipgate App) *** #### Which RTP / Sprachcodecs are used by sipgate? * G.711: approximately 100 kbit/s * GSM: 13 - 20 kbit/s * G.722/ HD *** #### Which codecs are used by [satellite](https://www.satellite.me/) and [sipgate App](https://clinq.com/)? * Opus: 6kbit/s - 510kbit/s *** #### How much data is used during a standard call? * VoIP call via G.711 / 10 Min. approximately 7,5MB * VoIP call via GSM / 10 Min. approximately 0,975-1,5MB *** If you are experiencing issues with lost audio or with speech quality please see [this](https://teamhelp.sipgate.co.uk/hc/en-gb/articles/204217301-Problems-making-and-receiving-calls) article. --- # 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://teamhelp.sipgate.co.uk/use-sipgate/telephony/what-are-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.