Bandwidth per call depends on the codec and packet size. Typical figures for IPv4 Ethernet at 20 ms packetisation, in each direction:
- G.711 / G.722: about 87 kbps
- G.726-32: about 55 kbps
- G.729: about 31 kbps
Sizing example
500 simultaneous G.711 calls need about 43.6 Mbps each way. If the server relays the media (RTP proxy), that traffic passes through the server in both directions, so plan the port with headroom.
Don’t forget
- SIP signalling is small but add margin.
- Leave 30–40% headroom for bursts.
- Low latency and jitter matter as much as raw bandwidth.
Try the VoIP bandwidth calculator to do the maths for your own numbers.