Calculate the on-the-wire bandwidth VoIP calls consume for a chosen codec, including RTP, UDP, IP and Ethernet overhead.
A G.711 call carries 64 kbps of audio but sends 50 packets a second, each wrapped in about 58 bytes of RTP, UDP, IP and Ethernet headers. That overhead adds roughly 23 kbps, so the real figure is closer to 87 kbps per call than the codec rate suggests. Provisioning trunks on the codec rate alone undersizes them by a third, and voice is the first traffic class users notice when a link saturates.
VoIP Bandwidth
Per-call kbps = codec payload + (header bytes × 8 × packets per second ÷ 1,000)
Per-call kbps = codec payload + (header bytes × 8 × packets per second ÷ 1,000) A G.711 call carries 64 kbps of audio but sends 50 packets a second, each wrapped in about 58 bytes of RTP, UDP, IP and Ethernet headers. That overhead adds roughly 23 kbps, so the real figure is closer to 87 kbps per call than the codec rate suggests.
Provisioning trunks on the codec rate alone undersizes them by a third, and voice is the first traffic class users notice when a link saturates.
This calculator takes 4 inputs: Concurrent calls, Codec payload rate, Packets per second, Per-packet header overhead. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.