Firewall Wizards mailing list archives

Re: FW: VOIP versus PBX


From: Roelof JT Jonkman <rjt () pobox com>
Date: Thu, 21 Jul 2005 13:31:17 -0700

Yehuda,

This is a bit of an opinion piece, but never the less may give some insight:

I'm a bit surprised that VOIP is getting so much traction. First thing
is voice is point to point, ip is a connectionless protocol. (Not to mention
that most of the underlying long haul infrastructure is really connection
oriented voice based: sonet.) So the dichotomy is that we're stacking a 
connection oriented thing on top of a connection less protocol on top
of connection oriented infrastructure. I would be one thing if you can
completely share the infrastructure and get the reliability similar to
conventional phone systems. However the general advocacy seems to be *not*
to share infrastructure. (At the minimum VLAN's is advocated) So the 'cost
savings' benefit is sort of out the window right there. The other thing is
complexity. VOIP is more complex to administer than a PBX. 

The only point I can see to VOIP is if you are backhauling a lot of voice
to a central location, and you have say more than a dozen offices or so.
Administratively, and cost wise you may save there. (Less cost for
conventional backhaul lines I'm guessing.)

If I were you I would price out both options, and include reasonable
guestimates of running costs for both. (And I would pad the running costs
guestimate of VOIP royally do to the inherent complexity.)

Depending on the size of your location (pbx) you may be subject to certain
sets of legal obligations to provide proper phone system function in cases
of emergencies. (power outage etc.) Even in my last office of 10 or so
folks I made sure that the mini lucent pbx/voice box was on UPS etc. Also
hardwired a regular POS analog phone to one of the incoming analog phone lines
in the break room. Readily accessible in case of emergency.

                roel

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