Bandwidth consumption and sample rates.
PCMA: 64kbit/s 8kHz
PCMU: 64kbit/s 8kHz
G729: 8kbit/s 8kHz Least consumption
G722: 64kbit/s 16kHz Best quality
Go to Account->Advanced to configure advanced settings
for account.
Sip Account: To choose which account to configure.
Audio Codec: R20 series support four audio codec: PCMA, PCMU,
G729, G722. Different audio codec requires different bandwidth, user
can enable/disable them according to different network environment.