NEC Electra Elite IPK II System User Manual page 687

Electra Elite IPK II
The PVA(X)-U( ) ETU supports only those codecs that are approved to provide toll-quality

speech paths. The following voice compression methods are supported for the IP CCH for
NEAX application:
G.711

G.729 – mid-range bandwidth

G.723 – lowest bandwidth

Each voice call will require at least the bandwidth listed in the following table:

Codec
G.711

-Law
G.729
G.723
Note 1:
Note 2:
Data calls (Modem Data) across the VoIP connection are only supported when G.711 Law

Codec is used.
The PVA(X)-U( ) ETU contains a regular TCP/RTP/IP stack that can handle real time

media. The PVA(X)-U( ) ETU, from the network administration perspective, is an end-point
on the IP network.
The PVA(X)-U( ) ETU with IP CCH for NEAX application loaded uses Common Channel

Interoffice Signaling over IP networks. Currently, this protocol does not allow
communications across networks where Network Address Translation (NAT) is performed.
The audio quality of speech connections depend greatly on the available bandwidth

between the PVA(X)-U( ) ETUs in the data network. As the internet is an uncontrolled data
network compared to an Intranet, you should use this application in Intranet WAN
environment, with known (or controlled and assured) Quality of Service (QoS).
If any network where the PVA(X)-U( ) ETU is connected uses NAT for connecting the voice

calls (including firewall), you should consult your network provider/administrator and
specifically request service for VoIP or real-time media support on your networks.
A static IP Address is required for each PVA(X)-U( ) ETU in the network.

K-CCIS – IP with PVA

-Law – highest bandwidth
Receive
Transmit
Data
Data Rate
Rate
90 Kbps 90Kbps
34 Kbps 34 Kbps
25 Kbps 25 Kbps
This includes the overheads of VoIP communication, including signaling.
In voice communications, particularly Internet telephony, the mean opinion score (MOS)
provides a numerical measure of the quality of human speech at the destination end of the
circuit. The scheme uses subjective tests (opinionated scores) that are mathematically
averaged to obtain a quantitative indicator of the system performance. The maximum for
the Mean Opinion Score is 5.0.
Time
Packetization
Between
Delay
Packets
20 ms 1.5 ms
20 ms 15.0 ms
30 ms 37.5 ms
Document Revision 4C
Default Theoretical
Jitter Buffer Maximum
Delay MOS
2 datagrams 4.4
(40 ms)
2 datagrams 4.07
(40 ms)
2 datagrams 3.87
(60 ms)
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