# What are codecs?

To be able to transmit acoustic signals from a sender to a receiver, they must first be converted into data. This task is carried out by a **codec** is handled by. A codec is a closely related pair of algorithms responsible for the **encoding and decoding** of data. With 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 higher compression of data packets and therefore require less bandwidth during transmission. However, this negatively affects quality. **Lossless codecs** transmit the data packets without compression and thus 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)

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* **Which RTP / voice codecs does sipgate use?**
* G.711: approximately 100 kbit/s
* GSM: 13 - 20 kbit/s
* G.722/ HD

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#### **Which codec do** [**satellite**](https://www.satellite.me/) **and** [**sipgate app**](https://clinq.com/)**?**

* Opus: 6 kbit/s - 510 kbit/s

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#### **What amounts of data are used in about ten minutes?**

* VoIP call via G.711 / 10 min. approximately 7.5 MB
* VoIP call via GSM / 10 min. approximately 1.5 MB

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#### **Are data channels ISDN (X.75) or Analog X.25 supported?**

No, not planned at the moment.


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