Speech Codecs Used in VoLTE Networks

𝐖𝐡𝐚𝐭 𝐚𝐫𝐞 𝐒𝐩𝐞𝐞𝐜𝐡/𝐀𝐮𝐝𝐢𝐨 𝐂𝐨𝐝𝐞𝐜𝐬?
Speech codecs are algorithms used to compress and decompress voice signals for transmission over the network. They convert analog voice signals into digital form, compress them to reduce the required bandwidth, and then decompress them at the receiving end for playback.

𝐖𝐡𝐚𝐭 𝐝𝐨 𝐰𝐞 𝐮𝐬𝐞 𝐢𝐧 𝐕𝐨𝐋𝐓𝐄?
Several audio codecs are commonly used in VoLTE (Voice over LTE) networks to transmit voice data during VoLTE calls. Speech codecs and codec rates play a crucial role in Voice over LTE (VoLTE) and can significantly impact the quality of Voice over IP (VoIP) calls, as measured by the Mean Opinion Score (MOS).

Are you curious about the various speech/audio codes found in VoLTE with different speech quality they offer? Here is a list of available VoLTE codecs below:

𝐀𝐌𝐑-𝐖𝐁 (𝐀𝐝𝐚𝐩𝐭𝐢𝐯𝐞 𝐌𝐮𝐥𝐭𝐢-𝐑𝐚𝐭𝐞 𝐖𝐢𝐝𝐞𝐛𝐚𝐧𝐝)
𝑩𝒊𝒕 𝑹𝒂𝒕𝒆: 6.6 𝘬𝘣𝘱𝘴 𝘵𝘰 23.85 𝘬𝘣𝘱𝘴
𝑺𝒑𝒆𝒆𝒄𝒉 𝑸𝒖𝒂𝒍𝒊𝒕𝒚: AMR-WB is known for its high speech quality. It provides wideband audio, which results in more natural and clear voice reproduction. This codec is commonly used in VoLTE for its superior audio quality.

𝐄𝐕𝐒 (𝐄𝐧𝐡𝐚𝐧𝐜𝐞𝐝 𝐕𝐨𝐢𝐜𝐞 𝐒𝐞𝐫𝐯𝐢𝐜𝐞𝐬)
𝑩𝒊𝒕 𝑹𝒂𝒕𝒆: 5.9 𝘬𝘣𝘱𝘴 𝘵𝘰 128 𝘬𝘣𝘱𝘴
𝑺𝒑𝒆𝒆𝒄𝒉 𝑸𝒖𝒂𝒍𝒊𝒕𝒚: EVS is one of the most advanced VoLTE codecs, offering excellent speech quality, even at low bit rates. It can adapt to varying network conditions, providing high-quality audio with minimal packet loss or jitter.

𝑩𝒊𝒕 𝑹𝒂𝒕𝒆: Variable, typically 12 𝘬𝘣𝘱𝘴 𝘵𝘰 64 𝘬𝘣𝘱𝘴
𝑺𝒑𝒆𝒆𝒄𝒉 𝑸𝒖𝒂𝒍𝒊𝒕𝒚: Opus is a versatile codec used in various applications, including VoLTE. It offers good speech quality and is adaptive to network conditions. Its flexibility in adjusting bit rates helps maintain quality in variable network environments.

𝐆.711 𝐏𝐂𝐌 (𝐏𝐮𝐥𝐬𝐞 𝐂𝐨𝐝𝐞 𝐌𝐨𝐝𝐮𝐥𝐚𝐭𝐢𝐨𝐧)
𝑩𝒊𝒕 𝑹𝒂𝒕𝒆: 64 𝘬𝘣𝘱𝘴
𝑺𝒑𝒆𝒆𝒄𝒉 𝑸𝒖𝒂𝒍𝒊𝒕𝒚: G.711 provides uncompressed audio, resulting in high speech quality. However, it consumes more bandwidth compared to other codecs. It may be used in specific cases where bandwidth is not a concern.

𝑩𝒊𝒕 𝑹𝒂𝒕𝒆: 48 𝘬𝘣𝘱𝘴 𝘵𝘰 64 𝘬𝘣𝘱𝘴
𝑺𝒑𝒆𝒆𝒄𝒉 𝑸𝒖𝒂𝒍𝒊𝒕𝒚: G.722 is a wideband codec that offers better audio quality than narrowband codecs like G.711. It provides a clear and natural-sounding voice.

𝐀𝐌𝐑-𝐍𝐁 (𝐀𝐝𝐚𝐩𝐭𝐢𝐯𝐞 𝐌𝐮𝐥𝐭𝐢-𝐑𝐚𝐭𝐞 𝐍𝐚𝐫𝐫𝐨𝐰𝐛𝐚𝐧𝐝)
𝑩𝒊𝒕 𝑹𝒂𝒕𝒆: 4.75 𝘬𝘣𝘱𝘴 𝘵𝘰 12.2 𝘬𝘣𝘱𝘴
𝑺𝒑𝒆𝒆𝒄𝒉 𝑸𝒖𝒂𝒍𝒊𝒕𝒚: While not as high-quality as AMR-WB, AMR-NB provides reasonable speech quality for VoLTE calls. It’s often used in situations where bandwidth is limited.

Mobile network operators typically make codec selection decisions based on a balance between speech quality and network efficiency.