User`s manual

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4.2.6 SIP VoIP Advanced Configuration
Smart-QoS:
If this function is enabled, when VoIP call is occurred, the other data will be automatically
reduced traffic which across the internet in order to guarantee the voice bandwidth.
Silence Compression:
If this function is enabled, when silence is occurred for a period of time, no data will be sent
across the network during this period in order to save bandwidth.
DTMF Method for SIP:
After the VoIP call is connected, when you dial a digit, this digit is sent to the other side by
DTMF tone. There are three methods of sending the DTMF tone. The first one is “in band”,
that is, sending the DTMF tone in the voice packet. The second one is “RFC2833”, that is,
sending the DTMF tone as a RTP payload signal. The third one is “SIP Info”, that is, sending
the DTMF tone as a SIP signal. Sending DTMF tone as a signal could tolerate more packet
loss caused by the network. If this selection is enabled, the DTMF tone will be sent as a
signal.
Voice Codec option:
The Codec is used to compress the voice signal into data packets. Each Codec has different
bandwidth requirement. There are four kinds of Codec, G.723, G.729AB, G.711_u and
G.711_A. The default value is G.723.
FAX Mode Option
T.30/T.38 real-time FAX compliant Voice/FAX auto-switch.
The T.38 is a “Real Time Group 3 Fax Communication over IP network” format. That’s
meaning it’s a protocol for Fax over IP. You have to enable this function