What does Codec mean in the world of VoIP and how much bandwidth does it require?

VoIP providers assume you have a broadband internet connection. DSL, which stands for Digital Subscriber Link, cannot reach 10 Mbps, while a regular cable connection can reach up to 30Kbs. Keep in mind that VoIP is full duplex , meaning VoIP can receive and send data at the same time. ISPs emphasize high download speeds for streaming and downloading music and videos, but for VoIP, you need to send data at high speeds, so you should consider upload speed as your benchmark. Also remember that 1Mbps = 1024 Kbps.

The Codec type works by encoding and decoding audio signals. The most commonly used type of Codec is called G.711, and uses 64 kilobits per second plus additional overhead for security, which can be applied to an IP bandwidth of 80-90Kbps. But, G.711 does not use compression. You can use other codecs that compress the data to use less bandwidth, with lower quality, but still suitable for most conversations.

To get VoIP calls whose quality is comparable to PSTN, you will use a codec whose type and type is called G.729. G.729 is a codec favored by VoIP providers as a “bandwidth saver,” so they can connect slower connections. G.729 compresses 64Kbps to just 8Kbs, a compression ratio of 8 to 1, but in practice you get bandwidth savings of about 3 or 4 to 1. The G.729 codec uses around 24-30Kbps.

If you're willing to sacrifice call quality, your provider can use a codec called G.723.1. The compression ratio can be as high as 12 to 1. G.723.1 compresses the signal to 5,6 or 6,4 kilobits per second, resulting in a bandwidth requirement of 16,27Kbps or 17,07Kbps. In Megabits per second, it is as low as 0,0159.