SIP Protocol Stack
VOIP Codec Comparison
| Codec | Data Rate | Typical Datagram Size | Packetization Delay |
| G.711u | 64.0 kbps | 20 ms | 1.0 ms |
| G.711a | 64.0 kbps | 20 ms | 1.0 ms |
| G.726-32 | 32.0 kbps | 20 ms | 1.0 ms |
| G.729 | 8.0 kbps | 20 ms | 25 ms |
| G.723.1 | 6.3 kbps | 30 ms | 67.5 ms |