User manual

Chapter 3 Configuration
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Configure VAD: VAD (Voice Activity Detection) is a function to detect voice activity during one
conversation. It is to efficiently utilize the bandwidth by not transmitting “empty” voice packets when both
sides remain silent. In the meantime, a comfort noise could be generated (occupied little bandwidth).
Disable VAD: No VAD function
Enable VAD with Comfort Noise: a comfort noise will be generated (CNG)
Enable VAD with Standard SID: VAD will be done with standard SID (Security Identifier).
Enable VAD and Suppress SID: When silence is detected, the VoIP device will not send any
packets to the network and the transmission of packets will be paused until voice is detected again
Configure Echo Cancellation: Four options are available including disable echo cancellation, enable
echo cancellation, enable echo cancellation with NLP, enable echo cancellation with CNG_NLP.
Start Attenuation: Setting the Start Attenuation timer.
Max Attenuation: Setting the Max Attenuation timer.
Echo Cancellation Tail Length: Setting the Tail Length.
Configure DTMF Relay: DTMF (Dual Tone Multi Frequency).
None: selecting none for sending DTMF tone in original audio form.
RFC 2833: sending voice with RTP packets
Configure Hook Flash Time: This parameter specifies the maximum time in mSec of Hook flash. For a
Hook flash to be detected , there should be an on-hook followd by an off-hook within “ Hook Flash Max
Time” mSec.
Configure Debounce Time: There are two parameters to be configured here.
OnOffDebounce Time: A delay in mSec before informing on an off-hook event to ensure it is not a
spike. If during that time an on-hook event is received , the two events will be ignored. If 0 , no
debounce will be done.
OffOnDebounce Time: A delay in mSec before informing on an on-hook event to ensure it is not a
spike. If during that time an off-hook event is received , the two events will be ignored. If “Hook
Flash Max Time” is configured , it MUST be more than OffOnDebounce. If it is 0 , no debounce
will be done.
Codec Preference: Set the priority of voice compression in terms of voice codec for outgoing message
and indication of incoming message accompanied with codec preference information. Priority 1 owns the
top priority.
G.711U / G.711A: G.711U and G.711A are the basic non-compressed encoder/decoder technique.
You can have very good sound quality but 64kbps bandwidth is needed.
G.729A: Using G.729A to encoder/decoder voice information into a single packet reduces the
bandwidth consumption (8kbps only) while you still can have good sound quality.