CounterPath X-Lite 4 for Windows User Guide - Manual (Page 48)

CounterPath Corporation
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Supported Codecs
Codec Narrowband Wideband
Broadvoice-32 3
Broadvoice-32 FEC 3
DVI4 3
DVI4 Wideband 3
G.711aLaw * 3
G.711uLaw * 3
GSM 3
iLBC 3
L16 PCM Wideband 3
Speex 3
Speex FEC 3
Speex Wideband 3
Speex Wideband FEC 3
* Generally, at least one of these codecs must be enabled in order to
place a PSTN (land line) call.