September 02, 2004, 12:00 AM — Recently, I had the opportunity to write a white paper on the topic of
IP Telephony (IPT) security.
In talking with executives from Cisco and 3Com, the two leaders in
enterprise IPT, one key point became very clear: Telephony should be
viewed as simply another way to leverage a corporation's IP network
infrastructure. Bits are bits, after all. Layer 3 of the seven-layer OSI
reference model, the network layer, cares not one bit (sorry about that)
whether the bits it transports are from a telephone conversation, word
processing documents, or pictures of little Patrick's soccer game.
When you look at IPT this way, it's not that far of a leap for solutions
integrators with the appropriate resources to ponder the benefits of
offering telephony solutions.
We're not talking VoIP, the "voice over IP" technology that has come to
be associated mostly with consumer-level products. IPT is different. IPT
is telephony solutions for the corporate enterprise. Is the Internet
involved? Not necessarily. IPT is perfect for the corporate campus,
running within the corporate network. In that regard, it is unfortunate
IP is short for Internet Protocol. Perhaps calling it RCP (really cool
protocol) would have been better. But the Internet is there, so
connecting to branch offices, of course, can be accomplished rather
The beauties of IPT are several.
For the corporation, there's no longer a need to run separate, distinct
networks for voice and data. The old PBX-based system and its switching
equipment can be removed and put out with the trash. Those closets full
of wire bundles with their thousands of ultrathin twisted pairs that
lead to individual phone extensions can be reclaimed as space usable for
a more productive purpose. Besides, walking into one of those wiring
closets usually results in an experience akin to entering a church
sanctuary: awe, mysticism, and, of course, an immediate yielding to a
higher authority, in this case the third-party "telephone guy." Why deal
with that when the existing IP network is willing?
For the integrator, you get to sell IP telephony servers, lots of
IP-based desktop telephones, firewalls for the necessary bolstering of
security (more about that later), and wonderful telephony applications
that leverage not just the network, but the data files already living
there. You also get to run more Cat5 cabling, probably sell more
switches, offer training, management software, and more.
Not surprisingly, security plays a big role in designing and
implementing an IPT system. The risks are no greater than with a PBX
system, but they are different. IPT is safest when run on a different
network segment than data. Hardening the network helps secure it against
the ills data can fall prey to --- denial of service, spoofing, packet
sniffing, viruses, worms, and others.