VL on VoIP       Issue 71


By William Flanagan

We've heard much more interest expressed lately about IP telephony,
a/k/a Voice over Internet Protocol (VoIP). Trials or tests have appeared
almost everywhere. One large client found thousands of IP phones
installed locally, without central coordination, producing islands of
incompatible VoIP systems. It's deja vu all over again, something like
the inexorable spread of the first PCs or how fax machines and cell
phones became essential to business.

How are you coping? Let's talk about that, and what others are doing in
the VoIP arena.

With this issue, ViewsLetter shifts focus from high availability
services to VoIP. HA is still a factor--the telephone has a very high
expectation for availability, traditionally called "five nines" or
99.999% uptime (down about 5 minutes a year). But moving from time
division multiplexing (TDM) to packet switching for voice (VoIP)
fundamentally changes how that goal is achieved (if it is achieved at all).

"Telephone people" need new knowledge and skills to stay on top of
telephony infrastructure in the future. PBX makers stopped development
on legacy TDM equipment so eventually everything will be VoIP on packet
networks. "Data people" who have experience in IP on Local Area Networks
(LANs) and wide area transmission also need to expand their knowledge.
They may not know the details of voice switching applications,
signaling, or interactions with the global Public Switched Telephone
Network (PSTN).

Consider troubleshooting voice quality on VoIP. The problem could
involve an application, a server operating system, switches and routers
on a LAN, a wide area network (WAN), firewalls, and those little
computers called IP phones. Not easy to sort out, but future
ViewsLetters will cover best practices, lessons learned, and the latest
tools of the trade to help you do it.

Because we're technical gurus, many issues will look at the hardware and
software, at configurations and network architecture, and how to make it
work well. But the business aspects won't be ignored. We'll examine
various claims for VoIP in the area of cost reductions (often hard to
realize) and increased features and functionality (which may take more
work than expected to convert into greater business efficiency). Again,
there are practices and lessons that should be of value to you.

Security is important to both technical staff and management, so we'll
spend a lot time on this topic. In addition to the vulnerabilities of
generic servers and networks, VoIP brings in a new set of difficulties
for system operators. For example, the problems associated with VoIP
connections crossing a firewall are many (randomly assigned UDP ports,
for just one), with many possible solutions.

VoIP is changing very fast. The Session Initiation Protocol (SIP), the
format that is winning the race against H.323 and proprietary signaling,
has 50 or more study groups working on extensions to deliver additional
features. The many Forums are working on new standards and updates that
will impact buying decisions in future years. We'll be watching what
they're up to and report often.

Stay tuned for answers. We're here to help.