User guide

Common VoIP attributes: QoS, Media and DTMF-Relay QoS
iMG/RG Software Reference Manual (Voice Service)
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voip ep SIGNALING LIST
voip ep SIGNALING REMOVE
6.4 Common VoIP attributes: QoS, Media and DTMF-Relay
The following section details voip attributes that are typically used to handle voice quality and that are common
for both the two main VoIP protocols (SIP and MGCP).
In some specific cases some commands are effective only when a specific voip protocol is selected (see the
comand details).
All the following commands can be entered only after the voip protocol has been enabled.
6.4.1 QoS
iMG/RG/iBG devices allow to specify a specific DSCP/TOS priority value to the originated VoIP traffic.
DSCP and TOS are mutually exclusive because they refers to the same IP Header field using only a different
number of bits (3 bits in case of TOS, 6 bits in case of DSCP) and assigning different packet classification accord-
ingly to the TOS or DSCP value.
The command VOIP QOS SET DSCP is used to set the DSCP value while the VOIP QOS SET TOS command
is used to set the TOS value. The two commands are mutually exclusive: only DSCP or TOS can be configured.
Attempting to configure the TOS attributes after having configured the DSCP attributes (or viceversa) will
result in a conflict failure. It’s necessary reset the DSCP attributes (or TOS) befor setting the TOS attributes
(or DSCP).
It’s possible differentiate DSCP/TOS values for VoIP signalling packets from the DSCP/TOS values for the media
streams.
The command voip qos set dscp/tos signaling-protocol specify the DSCP/TOS values only for VoIP signaling
packets originated by iMG/RG/iBG devices.
The command voip qos set dscp/tos media-protocol specify the DSCP/TOS values only for VoIP media packets
originated by iMG/RG/iBG devices.
If signalling-protocol or media-protocol is not specified, the DSCP/TOS values are set to the same value for
both signaling and media packets.
6.4.2 Media
iMG/RG/iBG devices allow to specify a specific pool of IP UDP ports to be used for media (RTP) transport.
Each even media port is paired with the subsequent odd portand assigned to RTP or RTCP streams respec-
tively.
Then maximum number of simultaneously streams is therefore half of the size of the media range.