User's Manual Part 2

Grandstream Networks, Inc. GXV3175 USER MANUAL Page 44 of 68
FIRMWARE VERSION 1.0.0.32 Updated : 11/2010
with the up and down buttons. It is recommended to use the default
setting “PCMU”; if other vocoders are chosen, there could be an
audio transmission error.
Preferred Video Codec Selects the preferred video codec from the available list. It is
recommended to use H.264.
H.264Payload type Selects the dynamic H.264 codec payload type (ranges from 96-127).
The default setting is 99.
H.263+ Payload type Selects the H.263+ codec payload type (ranges from 96-127). The
default setting is 103.
L16-256 Payload type Selects the L16-256 codec payload type (ranges from 96-127). The
default setting is 103.
H.263 Encoder
Resolution
Selects the resolution (CIF/QCIF) used for H.263 codec. The default
resolution is CIF.
Silence Suppression This controls the G723/G729 silence suppression/VAD. If set to YES,
when no audio is detected, the phone will send a small number of
VAD packets (instead of audio packets). If Set to NO, this feature is
disabled. The default setting is NO.
Voice Frame per TX This configures the number of voice frames transmitted per packet. (It
is recommended to set this based on the Ethernet IS packet limitation
– 1500 Byte or 120kb/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 and the actual frames transmitted during
the in payload call.
For example: if the codec is configured to be G.723 and “Voice
Frames per TX” is set to 2. Then in the INVITE request, the “ptime”
value for SDP will be 60 ms. This is because the G723 voice frame is
30 ms. Similarly, if the setting is 2 and the codec is G729 or G711 or
G726, the “ptime” value for SDP in the INVITE request will be 20 ms.
If the voice frames per TX configuration exceeds the maximum value
allowed, the phone will choose the preferred codec and use the
maximum value allowed.
The maximum value is 64 frames.
Adjusting these values will also change the jitter buffer. The phone
has an algorithm for setting the jitter buffer and the jitter buffer rate is
around 20-200ms.
For end-users, it is recommended to use the default setting, as
incorrect settings may influence the quality of audio.
G723 Rate This defines the encoding rate for G723 vocoder, and can be 6.3Kb/s
or 5.3Kb/s. Please confirm with your service provider.
Jitter Buffer Type Users can select either Fixed or Adaptive based on network
conditions. The default is Adaptive.
Jitter Buffer Length User can select Low, Medium, or High based on network conditions.
The default is Medium.
Account/Call Settings
Dial Plan Prefix Sets the prefix added to each dialed number.
Dial Plan Dial Plan Rules: