CUBE uses codecs to
compress digital voice samples to reduce bandwidth usage per call. Refer to
Table 2 to see the relationship between
codec and bandwidth utilization.
on a device (configured as CUBE) allows the device to act as a demarcation
point on a VoIP network and allows a dial peer to be established only if the
desired codec criteria are satisfied. Additionally, preferences can be used to
determine which codecs are selected over others.
If codec filtering
is not required, CUBE also supports transparent codec negotiations. This
enables negotiations between endpoints with CUBE leaving the codec information
below show how codec negotiation is performed on CUBE. Two VoIP clouds need to
be interconnected. In this scenario, both VoIP 1 and VoIP 2 networks have G.711
a-law configured as the preferred codec.
Figure 1. Codec
Negotiation on CUBE
In the first
example, the CUBE router is configured to use the G.729a codec. This can be
done by using the appropriate codec command on both VoIP dial peers. When a
call is set up, CUBE will accept only G.729a calls, thus influencing the codec
In the second
example, the CUBE dial peers are configured with a transparent codec and this
leaves the codec information contained within the call signaling untouched.
Because both VoIP 1 and VoIP 2 have G.711 a-law as their first choice, the
resulting call will be a G.711 a-law call.