G.711 — The Universal Codec

Why G.711 Is the Lingua Franca

Every SIP device in the world supports G.711. Every PSTN gateway speaks it natively. It's the codec you fall back to when nothing else works, and it's the codec that defines baseline voice quality.

G.711 isn't clever. It doesn't compress. It simply takes the PCM samples from Lesson 5 and ships them across the network. Its "algorithm" is companding (μ-law or A-law) — that's it. No prediction, no modeling, no transforms.

This simplicity is its greatest strength:

• Zero algorithmic delay: No buffering frames for analysis; each sample is independent
• No computational cost: Any processor can encode/decode G.711 trivially
• Maximum compatibility: Every device supports it
• Highest narrowband quality: No compression artifacts; the only impairment is quantization noise

The tradeoff is bandwidth. G.711 uses 64 kbps of codec bitrate — the most of any standard voice codec. But "64 kbps" is only part of the story.

Packetization: Turning a Continuous Stream into Packets

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