Grandstream Networks WP820 Administration Manual page 24

DTMF
DTMF Payload Type
Enable Audio RED with
FEC
Audio FEC Payload Type
Audio RED Payload Type
Silence Suppression
Minimum Jitter Buffer
Length
Maximum Jitter Buffer
Length
Voice Frames Per TX
Preferred Video Codec
Enable Video FEC
Enable RFC5168 Support
Default is 123.
Specifies the mechanism to transmit DTMF (Dual Tone Multi-Frequency) signals. There are 3
supported modes:
● In audio, which means DTMF is combined in the audio signal (not very reliable with low-bit-
rate codecs);
● RFC2833, which means to specify DTMF with RTP packet. Users could know the packet is
DTMF in the RTP header as well as the type of DTMF.
● SIP INFO, which uses SIP INFO to carry DTMF. The defect of this mode is that it is easily to
cause desynchronized of DTMF and media packet if the SIP and RTP messages are required
to transmitted, respectively.
The default setting is "RFC2833".
Configures the RTP payload type using RFC2833 that indicates the transmitted packet contains
DTMF digits. Valid range is from 96 to 127.
Default value is 101.
If set to "Yes", FEC will be enabled for audio call.
The default setting is "No".
Configures audio FEC payload type. The valid range is from 96 to 127.
The default value is 121.
Configures audio RED payload type. The valid range is from 96 to 127.
The default value is 124
Enables the silence suppression/VAD feature. If it is set to "Yes", when silence is detected, a
small quantity of VAD packets (instead of audio packets) will be sent during the period of no
talking. If set to "No", this feature is disabled.
The default setting is "No".
Set minimum jitter buffer length based on network conditions.
The default value is 0ms.
Set maximum jitter buffer length based on network conditions.
The default value is 1000ms.
Configures the number of voice frames transmitted per packet (It is recommended that the IS
limit value of Ethernet packet is 1500 bytes or 120Kbit/s). When configuring this, it should be
noted that the "ptime" value for the SDP will change with different configurations here. This
value is related to the codec used in the codec table or negotiate the payload type during the
actual call. For example, if the setting is set to 2 and the first code is G. 729 or G. 711, the
"ptime" value in the SDP datagram of the INVITE request is 20 milliseconds. If the "Voice
Frame/TX" setting exceeds the maximum allowable value, the phone will use and save the
maximum allowable value for the selection of the first encoding. It is recommended to use the
default setting provided, and incorrect setting may affect the voice quality.
Preferred Video Codec
This parameter is to configure the preferred Video Codec used to receive and display video for
SIP calls on WP820. The default setting is H.264.
When enabled, the video sender will temporarily allocate part of the bandwidth to one data
channel to send FEC data to system, thus, to improve the video quality the WP820 gets. Enabling
this function will take up part of bandwidth and reduce call rate. The default setting is "Yes".
Enables/disables RFC5168 mechanism for video calls to WP820. RFC5168 allows SIP party to
request the sender to refresh its video frame in H.264.The default setting is "No".