Bandwidth depends on audio mode, the number of active voice streams, connected clients and the network path. CTI's published planning figures are approximately 2.2 kBytes/s per compressed audio stream and 22 kBytes/s per high-quality stream. Confirm the figures for the versions and codec used in your installation.
| Audio mode | One stream | Equivalent in bits | Ten streams, one receiving client |
|---|---|---|---|
| Compressed | 2.2 kBytes/s | 17.6 kbits/s | 22 kBytes/s, or 176 kbits/s |
| High quality | 22 kBytes/s | 176 kbits/s | 220 kBytes/s, or 1.76 Mbits/s |
The example multiplies the published per-stream rates; it is not a complete circuit-size recommendation. Allow for packet overhead, other radio data, encryption/VPN overhead where used, concurrent transmissions and other applications sharing the connection. Audio modes and compression can change between product versions.
Count the streams that actually cross each WAN link. Several remote clients receiving the same traffic can require several network streams; do not size the site's upload solely from the number of radio channels. A local client and a remote client also place different demands on the internet circuit.
Radio airtime is a separate limit: more internet bandwidth does not let two users talk independently on the same control-station channel. Measure latency, jitter and packet loss as well as throughput, and test realistic peak traffic before accepting a cellular or satellite link.