Codecs
The following codecs are supported:
| Codec | Models | Firmware | Bitrate | Sampling Rate | Notes |
|---|---|---|---|---|---|
G.711 a-law | D40, D45, D50, D60, D62, D65, D70, D80 | All released firmware | 64000 bps | 8kHz, Narrowband | Referred to in phone config as "PCMA" |
| G.711 u-law | D40, D45, D50, D60, D62, D65, D70, D80 | All released firmware | 64000 bps | 8kHz, Narrowband | Referred to in phone config as "PCMU" |
| G.726 | D40, D45, D50, D60, D62, D65, D70 | All released firmware | 32000 bps | 8kHz, Narrowband | Referred to in phone config as "G726-32" |
| iLBC, 30ms | D60, D62, D65 | 2.2.0.4 and greater | 13333 bps | 8kHz Narrowband | Referred to in phone config as "iLBC" |
| Opus | D60, D62, D65 | 2.2.0.4 and greater | 12000 bps | 8kHz Narrowband | Only one channel is supported at a time. Users should enable at least one other codec when using Opus to allow three-way calling. Referred to in phone config as "opus" |
| G.729a | D40, D45, D50, D60, D62, D65, D70 | All released firmware | 8000 bps | 8kHz, Narrowband | D60, D62, D65 models require user activation of codec, requires Internet access; codec will not appear in config UI without activation. Referred to in phone config as "G729" |
| Linear | D40, D45, D50, D60, D62, D65, D70 | All released firmware | 128000 bps | 8kHz, Narrowband | This codec should generally not be used outside of a LAN. Referred to in phone config as "L16" |
| G.722 | D40, D45, D50, D60, D62, D65, D80 | All released firmware | 64000 bps | 16kHz, Wideband | Referred to in phone config as "G722" |
| G.722.1, licensed by Polycom® | D60, D62, D65 | 2.2.0.4 and greater | 32000 or 24000 bps | 16kHz, Wideband | Referred to in phone config as "G7221" |
| Opus | D60, D62, D65 | 2.2.0.4 and greater | 20000 bps | 16kHz, Wideband | Only one channel is supported at a time. Users should enable at least one other codec when using Opus to allow three-way calling. Referred to in phone config as "opus" |
| Linear 16 | D40, D45, D50, D60, D62, D65, D70 | All released firmware | 256000 bps | 16kHz, Wideband | This codec should generally not be used outside of a LAN. Referred to in phone config as "L16-256" |
| G.722.1C, licensed by Polycom ® | D60, D62, D65 | 2.2.0.4 and greater | 48000, 32000, or 24000 bps | 32kHz, Ultrawideband | Referred to in phone config as "G7221" |
In order to limit MTU size for UDP-based SIP signaling, Digium phones only enable a limited subset of these codecs by default. Use of some codecs may require enabling them, which can be done via XML or DPMA configuration.