# Understanding Codecs

> Category: General
> Canonical URL: https://crazytel.com.au/knowledgebase/article/understanding-codecs

A brief exposé on commonly found codecs -- nothing technical, only the basics!

# Understanding CODECs








## Overview



This article aims to highlight the key differences between codecs. This article has been written to be easily digestible, and easy to search.













## Common Codecs



These Codecs are commonly used by Crazytel.













### PCMA | G.711a:



* A-law: A common audio coding standard used primarily in Europe and other parts of the world.



* High quality: Provides good audio quality but has a high bandwidth requirement (64 kbps (dial-up speed)).













### Opus:








* Modern and versatile: A modern, flexible audio codec designed for a wide range of applications, including voice, music, and video conferencing. 



 



* High quality and efficiency: Offers excellent audio quality at various bitrates, making it suitable for different network conditions.













### T.38:



* Fax over IP: Another standard for fax over IP, often considered more robust and reliable than H.232.



 








## Uncommon Codecs



Although Crazytel won't block transmissions using these protocols, we don't recommend using them.













### PCMU | G.711µ:



* µ-law: Another common audio coding standard, primarily used in North America and Japan. 



 



* High quality: Similar to PCMA in terms of audio quality and bandwidth usage.













### G729:








* Low-bitrate: Designed for low-bandwidth networks, offering good voice quality at a much lower bitrate (8 kbps) than G.711.



* Popular for VoIP: Widely used in VoIP systems due to its efficient bandwidth usage. 













### H.232:








* Fax over IP: A standard for transmitting fax signals over IP networks.



* **Not an audio codec:** Specifically designed for fax communication.