Advancing The Advanced
BY STEFAN KARAPETKOV
With quality of service and reliability consistently improving, more
companies are replacing their circuit-switched PBX systems with more
advanced and cost-effective IP telephony implementations.
Cahners In-Stat recently reported the three-year old Voice-over-IP
(VoIP) handset market reached $1 billion in 2001 and estimates the market
for IP voice equipment will quadruple by 2006.
Whether a company is moving to a new building and needs to cut
operational costs or needs to increase connection efficiencies between
smaller or remote offices, installing an IP phone brings many benefits.
In addition to creating just one communications infrastructure to
maintain and administer, an upgradeable IP phone can be connected to a
variety of voice communication systems and unplugged and connected to the
LAN in another room, floor or building. For companies with teleworkers
and/or remote offices that have VPNs to headquarters, an IP telephony
solution is an especially attractive offering, as no additional
teleworking hardware and software is necessary nor is a second analog line
required for signaling.
However, with an influx of IP phones to choose from, how can companies
be sure hard-to-come-by dollars are invested in the right phone device ï¿½
a phone device that will help realize the full capabilities and benefits
of an IP system?
There are a number of points to consider before implementing IP phones
to ensure optimal voice quality and data transfer:
- A choice IP phone will have a second Ethernet port and a true LAN
switch built in, ensuring that PC traffic does not interfere with
- Heavy data traffic through the switch can negatively affect voice
quality. To avoid this, choose an IP phone with the ability to switch
LAN traffic and support Virtual LANs and Quality of Service.
- A phone with a jitter buffer, powerful processor and short voice
frames (20-30ms) also helps improve voice quality.
- Select an IP phone that has multiple protocol support (SIP, H.323,
H.450, proprietary feature-rich protocols, etc.) and is easily
upgradeable. This will protect the initial investment should
future-developed protocols become a requirement.
- Consider an IP device that supports standards for management and
operation (DHCP, SNMP, HTTP, and SNTP) and will integrate with
existing management systems.
- For larger installations, it is important to evaluate an IP phone
for Power over LAN (PoLAN) capabilities. PoLAN allows for power hub
connections to Uninterrupted Power Supply (UPS), making the phones
operational even when a power failure occurs.
- Choose a manufacturer with global availability and distribution
capabilities. This eases international expansion and eliminates the
need to search for another manufacturer abroad.
- A warranty is important. Be sure that the manufacturer offers an
extended warranty. A 90-day warranty is common, but 1-year warranties
are available as well.
There are many components involved in an IP telephony system. An IP
phone that improves voice quality, has fast call setup and a single line
to the desktop is just part of a successful IP PBX installation. But
having the right phone in place means being one step closer to IP
Stefan Karapetkov is group manager ï¿½ Product Management ï¿½
Telephones and Soft Clients at Siemens Enterprise Networks. Please visit
their Web site at www.siemens.com.
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