2N Helios IP User manual, 1510 v1.13 - Manual (Page 85)

Configuration 3.3
85
Transmission Quality Settings
Jitter compensation
Set the buffer length to compensate jitter caused by variable delays between
incoming RTP packets. A longer buffer mans a better transmission quality yet a
higher transmission delay.
QoS DSCP for audio
Set the priority of the audio transmitting packets in the network. The value is
copied into the ToS (Type of Service) field in the IP packet header.
Caution
 Wrong settings may deteriorate the transfer quality. Do not change this
parameter if you are not sure. The change in transfer quality will show
only in case the network components support this service.
Figure 3.24 Audio Codec Settings
DTMF Receiving and Sending
Defines how DTMF signalling should be received and sent. Check the opponent‘s
parameters for correct settings.