ESI 24-Key Digital Feature Phone Specifications download pdf (Page 11)

ESI Communications Servers Product Overview

Differentiated Services (DiffServ)

This standard is primarily used with remote IP Phones

and Esi-Link installations in a WAN environment. This

protocol allows IP voice packets to be prioritized over

data transmission in LAN/WAN environments whose

routers provide prioritization. As with all QoS provisioning

within a LAN or WAN, the network components, such

as routers and switches, must be able to support, and

be configured for Quality of Service.

Some Internet connections may not support DiffServ.

Contact the customer’s ISP to determine whether it

supports DiffServ.

Dedicated voice over IP resources

A codec is used to take the analog spoken voice, encode

it as an IP packet so it can be compressed and transmitted

as a “data” packet. When received by another IP device

(IP Phone or other Esi-Link system), the IP packet is

decoded so that it is converted back into analog voice.

Communication via IP is not possible without codecs.

Three types of industry-standard codecs are used by

ESI’s 48-Key IP Feature Phone II and IVCs: G.711,

G.726, and G.729. This refers to the amount of

compression that a voice packet will undergo when

being converted into an IP packet.

G.711 is the non-compressed standard from which all

other compression standards are established. IP Phones

that are locally installed use G.711.

Each 48-Key

IP Feature Phone II has built-in G.711 and G.726 codecs.

Additionally, each channel of the IVC has dedicated

G.711 and G.726 codecs for conversion between

unlike compression standards. This conversion ability

of the IVC allows intelligible audio between remotely-

installed and locally-installed IP Phones.

Calls to or from a remotely-installed IP Phone use standard

compression rates of G.726 (calls to/from the IVC) and

G.729 (calls to/from Esi-Link channels). This reduces

latency in the IP conversation and minimizes dropped or

lost packets. Each of the 24 channels on the IVC has a

dedicated G.726 codec to support the connection of

remotely installed IP Phones. The Esi-Link IVC is

equipped with 24 dedicated G.729 codecs. By dedicating

codecs on each available IVC and Esi-Link IVC channel,

an IP Phone or Esi-Link user will never be denied the

ability to place or receive a call due to the lack of a codec.

Notes: The ESI-50 uses only the G.726 speech

compression algorithm and, therefore, can be in

an Esi-Link network with only other ESI

Communications Servers set to G.726. ESI’s

IVX

X-Class and IVX E-Class systems, as well

as the original ESI-600 (prior to system software

version 16.2.0) use only the G.729 speech

compression algorithm; thus, an ESI-50 cannot

be in an Esi-Link network with these systems.

Local and remote installations of VIP Softphone use G.726.

Power over Ethernet (PoE)

ESI’s 48-Key IP Feature Phone II complies with the

IEEE 802.3af standard for powering devices over a

customer’s existing local area network. This enhancement

requires the customer to install the appropriate PoE

network components, such as switches and routers.

The 48-Key IP Feature Phone II can also be powered

by using the optional 48VDC adapter. There are many

benefits to designing an IP telephony application with

Power over Ethernet capabilities:

• By using the local area network to power the IP

Phones, a consistent voltage is provided to all

phones without the fluctuations that frequently occur

in commercial office buildings.

• Since all power is provided from one location, a

single UPS system can be used to protect the IP

Phones from power surges, brown-outs, and other

electrical anomalies.

• Powering the IP Phones via the customer’s LAN

saves the cost and inconvenience of providing a

fused power strip at each IP Phone placement.

ESI has tested several Power over Ethernet devices for

compatibility with its PoE IP Phones:

• Cisco Catalyst 3560 24-port 10/100T PoE

• Adtran Netvanta 1224 PoE

• 3Com Superstack 3 4400 switch power

• 3Com PW130

In addition, the following mid-span Power over Ethernet

devices have been tested:

• 3Com 3CNJPSE24 24-port Midspan Solution

• D-link DWL-P1012 12-port PoE Midspan

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ESI 24-Key Digital Feature Phone Specifications Page 11

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