Which codec is commonly used by 3CX for VoIP calls?

The commonly used codec by 3CX for VoIP calls is Opus. Opus is highly versatile and offers excellent quality across a wide range of bit rates and network conditions, making it particularly well-suited for VoIP. It can adapt to varying bandwidths, which is crucial in ensuring clear communication even when network conditions fluctuate. This codec supports both narrowband and wideband audio, allowing for high-definition voice quality.

G.729 is also a popular codec in VoIP applications, specifically known for its low bandwidth usage, which can be advantageous in certain scenarios. However, it does not provide the same level of audio quality and versatility as Opus. G.722 is a wideband codec that offers better audio quality than narrowband options, but it still lacks the adaptability and efficiency found in Opus. MP3, primarily designed for music compression, is not suitable for VoIP calls due to its latency issues and lack of support for real-time voice transmission, making it an unfit option for this use case.