G.711 is not dead, and that is fine
G.711 was standardised in 1972. It compresses nothing: 8,000 samples per second, 8 bits each, 64 kbps. It still carries a large share of PSTN traffic and a surprising amount of VoIP that touches the PSTN.
Why it persists
- Every gateway speaks it. Interconnecting to the phone network means G.711, full stop.
- No algorithmic delay. One sample, one byte. Compare that with any codec that needs
- It fails gracefully. Packet loss sounds like a click, not a robot.
a lookahead window.
Where it hurts
Bandwidth. A G.711 call is 64 kbps each way before headers, and RTP headers on small packets are not free. At 20 ms framing you are sending 50 packets per second per stream.
The practical rule
Compress on the access side, transcode at the gateway. Do not try to keep a compressed codec all the way to a PSTN handoff unless your gateway vendor explicitly supports passthrough for that codec.