In order to capitalize on the advantages proffered by VoIP,
as well as the efficiencies afforded by todayï¿½s LAN, advanced IP phones
are being developed in ever-increasing numbers, by an ever-greater array of
vendors, both here and abroad. One of the first IP phones out on the market
is the IP Centrex phone from UniData Communication Systems. This phone,
which runs through an Ethernet LAN connection, uses the H.323 version 2
protocol and supports G.711, G.723.1, and G.729 audio codecs. It has also
proven interoperability with other H.323 gatekeepers and switches, such as
AG Communications/Lucent Technologies iMerge product (which recently added
support for new IP Centrex software).
We were shipped two IP Centrex phones so that we could perform VoIP calls
from one phone to the other through our LAN. Connecting each of these phones
involved linking an Ethernet cable from the LAN jack in the wall to the
uplink port on the back of the phone and plugging in the power adapter.
Since these phones could not perform point-to-point calls by themselves,
we had to set up the gatekeeper software given to us by UniData. The
gatekeeper consisted of one floppy disk that can be installed on virtually
any Windows operating system. All we needed to do was unzip the main file,
click the executable, follow some basic installation steps, and accept the
default configurations. This took only a couple of minutes.
Configuring the IP Centrex phones was also a breeze. The most difficult
part of the process was pressing the Setup button for a second immediately
after unplugging, and then re-plugging the power adapter. Once we were in
the proper setup mode, we could specify the IP address, Subnet Mask, Default
Gateway, and DNS on the phone in a matter of seconds, although it would have
been even faster with DHCP support, which would be available if we had
hooked up the phone with a supported switch or a gatekeeper, such as iMerge.
For the initial configuration, all that was left to be done was set the
gatekeeper IP address to the phone, which is done through the regular Setup
menu. All in all, we had the gatekeeper and IP phones set up in about twenty
The documentation consists of a Quick Start Guide and a User License
Agreement for the gatekeeper software. The first half of the Quick Start
Guide gives instructions for the basic setup and configuration scheme of the
IP Centrex phone. The second half explains the basic features, some user
information, and some troubleshooting issues for the phone. While this guide
is not flashy and has grammatical errors throughout, it does cover most of
what a user might want to know about the phone, and provides many screen
shots and other graphics to illustrate the information more clearly.
The primary feature of the IP Centrex phone is for placing VoIP calls over
the LAN from one IP Centrex phone to the other. The phone is fully compliant
with H.323 version 2 and supports the G.711, G.723.1, and G.729 compression
codecs. The use of enhanced jittering compensation and bad frame
interpolation aid call quality.
The rest of the features of the IP Centrex phone, such as an LCD screen,
speakerphone, speakerphone mute, microphone and speaker ports for a
headphone, redial, ringer change/volume adjustment, speed dials, and caller
ID, are on most basic digital telephones. Future enhancements will include a
digital answer machine with voice recording, Internet services such as a
remote configuration manager, and a WML browser for accessing content. More
PBX functionality (e.g., call forwarding, three-way call conferencing, and
voice mail) is offered as a supplementary service, which is dependent on the
capabilities of the switch.
Once we had the gatekeeper and both IP Centrex phones up and running, we
first checked the network information to make sure it was correct, then
dialed the four-digit number of the other IP Centrex phone, and followed by
pressing the pound key. The other phone rang almost instantaneously, and we
saw the packet information run through the gatekeeper.
Upon pickup, we examined the sound quality and latency of the connection.
We could hear each person speaking very clearly with no echo and a minimal
amount of delay. The quality was that of a regular PSTN call, not that of a
VoIP call. As a matter of opinion, this particular VoIP call sounded better
than many "regular" phone calls we made that day. When making
additional VoIP calls using the IP Centrex phone, we had similarly excellent
As for the more fundamental telephony aspects of the IP Centrex phone, we
were able to create a speed dial for the first available button and make a
call to the other phone by pressing either of two buttons: F1 or the second
button on the upper left side of the phone (pressing the Menu button shows
which button should be pressed for specific speed dials). We expect that the
Menu button will offer more functionality in future versions of the IP
We assumed that we could not test the flash button for transferring calls
since we only possessed two IP Centrex phones. We did not have a third phone
to register with the gatekeeper, and pressing the flash key actually
disconnected the current call.
We quickly realized that if we registered a NetMeeting client to the
gatekeeper, we might be able to transfer or conference a call. While we were
able to register a NetMeeting client and make one-to-one calls through the
gatekeeper from NetMeeting to one of the IP Centrex phones, the connection
still hung up when trying a transfer or a conference call. With the addition
of this third registered connection, we became relatively sure that this was
because of the limited functionality of the gatekeeper we were using. A more
feature-rich gatekeeper would have allowed us to transfer or conference a
call. This test, however, did prove the IP Centrex phone's H.323
compatibility with NetMeeting.
We think it might interest our readers to note that we first became aware
of this product during ConvergeNET this past October at INTERNET
TELEPHONY CONFERENCE & EXPO in San Diego. It was there that we
originally performed some live demonstrations with the IP Centrex phone.
Instead of the simple gatekeeper we used for the above tests, we used
gatekeepers from Tundo and NetCentrex and connected to other H.323
compatible equipment. The voice quality was good doing these tests as well,
although not quite as excellent as the lab tests. Just as important was that
by performing these tests we proved that the IP Centrex phone was
interoperable with other company's equipment.
ROOM FOR IMPROVEMENT
While we have no complaints about the VoIP functionality of the IP Centrex
phone, the suggestions we do have are negated when the product is integrated
with AG Communications / Lucent Technologies' iMerge product. With this
collaboration, we hope to see client software for the PC (either Web-based
or Windows-based), which has right-click functionality and help files, and
allows for remote management functionality as well as desktop call control.
From the phone, it would also be beneficial to push Web pages, coupons, and
other material from the Internet to the LCD screen. While this might already
be in the works for UniData's WML browser, it is still worth mentioning.
In addition, we would recommend adding an analog port so that a fax or
modem could connect to the IP Centrex phone. The port could act as a digital
to analog converter to allow for such functionality as Fax over IP.
Calls can be made from an IP Centrex phone to a gatekeeper set up in an ISP,
CLEC, or ITSP, and then either continued as an IP call or hopped-off to the
PSTN and on to the "outside world." To achieve these ends,
UniData's IP-Centrex phone is one of the first of its kind, and is a quality
product, especially when it comes to its main purpose -- VoIP calls through
a LAN. The voice quality is among the best we've heard, and installation is
a snap. We award this product our highest honor for its ease of use and
installation, and the sheer quality of the VoIP calls.
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