Probably the key application that you can use with a converged
network, IP telephony (IPT), probably also needs the most
investigation. Many people simply think IPT is synonymous with
voice over IP; that would be a mistake. Ross Bentley sees what IPT
is, and isn't, and shows how you can make it work for you
According to Don Proctor, vice president and general manager at
Cisco and a man on the extreme upper lip of the IPT adoption curve,
what is described as convergence today differs from what people
defined as convergence five years ago. "Then, we talked about media
convergence: voice, video and data over the same network, and
reaping the advantages of no longer having to maintain multiple
networks," he says.
"But today we're entering a new phase: convergence of the user
experience. This represents the bringing together all of the
disparate communications systems people use - whether it's
voicemail, email, instant messaging or video conferencing - into a
single, unified communications experience."
What Proctor underlines here is the difference between simple
convergence and IP telephony - terms that, together with voice over
internet protocol (VoIP), are often used in the same breath, but in
reality are distinct from each other.
Discrete packets
Whereas convergence refers to the physical act of running both
voice and data traffic over one network, VoIP is the basic
mechanism for delivering voice over an IP infrastructure, including
the public internet, in digital form in discrete packets rather
than in the traditional circuit-committed protocols of the public
switched telephone network.
IP telephony, however, takes matters a step forward and allows VoIP
calls to retain the features and applications associated with a
traditional business telephony system, such as call handling,
forwarding, transfer and call back when free. It also allows
valuable extra functionality such as directory services, video
services and support for multi-channel contact centres. For mobile
workers, IP telephony provides further benefits such as
speech-enabled access to voice messages and directory
services
"IP telephony brings the full richness of PBX to an IP system, then
takes it to another level. It is the professional way of building
on VoIP," says Andy Clemens, senior marketing manager at BT
Business.
While you may already have realised the benefits of convergence,
Clemens says the next step is to upgrade to IP telephony. This can
be achieved by adding to an existing convergent (or hybrid) switch,
or provided by a new IP switch platform. "IP telephony brings even
more benefits to a business' converged network and makes deployment
more effective," he says.
As its name implies, IP telephony starts with the encoding of voice
into IP packets. With IPT it becomes necessary to prioritise the
voice packets over other data in order to avoid delays that would
seriously detract from speech quality. This is effected by a
technique known as Quality of Service (QoS), whereby all packets
are classified, and important packets (such as voice) are
prioritised above less important packets. So with IPT the LAN needs
to be QoS-enabled - which involves, for example, replacing switches
with QoS-enabled switches.
IP telephony is also associated with transferring VoIP calls over a
secure wide area network (WAN) or virtual private network (VPN) to
save on the cost of calls between sites. Again, the WAN or VPN
requires QoS, sometimes referred to as Class of Service (CoS). It
also requires the network to be properly dimensioned. Having done
this, IPT then enables calls between sites to be routed over the
company network to avoid traditional telephony costs
Circumnavigating PSTN
For this reason, organisations with multiple sites have most to
gain from IP telephony, according to Clemens. Significant cost
savings can be achieved by multi-site businesses using their own
network for IP telephony calls between sites and avoiding call
charges by circumnavigating the PSTN (public switch telephone
network).
Connecting satellite offices to the voice network is
straightforward compared with traditional telephony systems where
every site needed a switch. In the IP telephony world, a switch may
only be required at head office, with other sites just needing IP
phones.
This plug-and-play approach also makes remote working much easier,
enabling devices such as IP phones and soft phones with a
pre-configured IP address to be connected to an IP network with
pre-existing functionality and profiles. It also allows
comprehensive access to corporate functionality, features and
security as if staff were simply working in the office.
This flexibility makes network administration cheaper and simpler,
too. Your phones can be unplugged and moved at will, and an
administrator can easily make changes to movers, leavers and
joiners on any PC, without needing a dedicated terminal. This level
of simplicity also has benefits in terms of the scalability of your
network.
"IP telephony gives businesses a further return on their investment
in convergence, and allows them to promote a 'big company feel',
both internally and to their customers and suppliers," says
Clemens.
Internet telephony benefits
- Significant cost savings can be achieved by multi-site
businesses using their own network for IP telephony calls between
sites, thus avoiding call charges.
- Support for remote or smaller sites. Internet telephony can be
extended to other sites more cheaply than with traditional systems
because the remote sites may require only IP handsets to get up and
running.
- Better applications. Internet telephony allows your business to
adopt call centre and customer management applications much easier.
With common standards and open interfaces, implementation is
simpler and cheaper.
- The overheads of IT and communications management are reduced
with internet telephony. From an administrator's perspective,
internet telephony allows your entire voice and data network to be
viewed from a single management terminal.