NEC Electra Elite IPK II Features And Specifications Manual page 956

Document Revision 1
Routers
When purchasing a router for use with the Electra Elite IPK II IP feature, the minimum requirements
would be that it provide 10/100 Switch and QoS. Currently, VoIP Media Gateway (MG16) application for
the Electra Elite IPK II Megaco telephones can communicate over NAT firewall router. For the best
performance, NEC recommends connecting the Elite IPK II CPU and MG16 10/100 Switch and less
susceptible to network collision.
The priority control feature is required to prevent RTP packet loss. If a WAN is used for VoIP only and
the bandwidth is wide enough for the VoIP channel, then the QoS feature might not be required.
VoIP Bandwidth Calculation
A digital telephone system converts an analog voice signal into a stream of bits expressed in K bits per
second (where K is used to mean one thousand). For standard PCM digital encoding, this stream of bits
is 64 K bits per second. This is 64 K bps in each direction (transmit and receive).
To improve transmission efficiency, this bit stream is compressed using a standard compression
algorithm such as G.729. The result is still a bit stream, but with fewer bits per second. For example,
G.729 will reduce the 64 K bits per second to a bit stream of 8 K bits per second.
This bit stream is then divided into chunks (called Voice Samples or Voice Frames) that can be placed in
packets for transmission over a data network.
This reduced bit stream is examined repeatedly in fixed time intervals. This examination time is called
the Voice Frame Interval. This is the time used to collect the bits for one Voice Frame. The Voice Frame
Interval is expressed in milliseconds (ms). A millisecond is one thousandth of a second.
IP Hardware
ETUs:
Signals the gateway with VoIP communication.
IPK II CPU -
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- VoIP ETU provides a 16-channel voice packet gateway unit and works as a media
MG 16
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gateway. VoIP multiline terminal-to-VoIP multiline terminal can talk without using any DSP
resources using the peer-to-peer feature.
- Provides an 8-port switching hub for use with the Electra Elite IPK II system.
HUB Card
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IAD(8)-U10 ETU - VoIP ETU provides eight channels for supporting Megaco Stations on an IP
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CCISoIP network.
Terminals:
- An Electra Elite IPK II ITH 4D/8D/16D-2/3 button multiline IP telephone.
IP Phone
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- An IP adapter connects to a multiline terminal.
IP Adapter
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The telephone with the adapter installed is also referred to as the Dterm IP telephone.
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Electra Elite IPK II
Voice Over Internet Protocol (VoIP)