I didn't ask about 911 tracking, but I would assume since all phone =
calls are handled centrally at their location, and they are providing =
the internet link and the phone service, they should be able to do 911 =

They told me that the desktop instruments are powered by POE switches - =
I suppose those can be backed up by battery and generator if needed. All =
routing equipment along the path to the internet would need to be backed =
up also. This is anyway irrelevant because it's replacing a PBX with no =
power protection.

I don't know enough about QOS to know how a host in a different vlan =
than the phones can cross the vlan to shut down the phone network but I =
do know enough to ask.

From: Pollock, Joseph [mailto:PollockJ@evergreen.edu]=20
Sent: Thursday, July 21, 2005 1:40 PM
To: Yehuda Goldenberg; firewall-wizards@honor.icsalabs.com
Subject: RE: [fw-wiz] VOIP versus PBX

Other issues:
1.=A0=A0=A0 How does the vender plan to handle 911 location tracking?
2.=A0=A0=A0 The typical PBX has battery backup and, often, emergency =
generator support, and powers the desktop instruments.=A0 How does this =
compare to your network infrastructure?=A0 Is your current phone system =
considered an emergency communication component at your company?=A0 Is =
your network fully power protected in case of power outages?
3.=A0=A0=A0 There have been some quality reviews of VoIP gear recently =
(I don't know the methodology or quality of the reviews) that indicate =
that audio quality is more like a cell phone than a typical wired phone, =
among other characteristics, and that overall reliability is not yet up =
to traditional PBX standards.
=A0=A0=A0=A0=A0=A0 I'm not even going to touch on IP issues like DOS =
attacks or infected hosts overwhelming the QOS - I'd like to see a =
vender demonstrate that.
Joe Pollock
Network Services
The Evergreen State College

From: firewall-wizards-admin@honor.icsalabs.com =
[mailto:firewall-wizards-admin@honor.icsalabs.com] On Behalf Of Yehuda =
Sent: Friday, July 15, 2005 6:41 AM
To: firewall-wizards@honor.icsalabs.com
Subject: [fw-wiz] VOIP versus PBX
Our company is looking to replace an antiquated phone system.
I was leaning towards using a traditional PBX, because I figured that it =
would be more reliable and it wouldn't be subject to the problems of IP =
One vendor is trying to get me to change my mind about that. He claims =
that we can keep the voice and data networks completely separate by =
running vlans. The IP phones have vlan switches on them and one wire can =
be run to each desk and the pc and the phone can be on separate vlans.
I was concerned that problems on the data network such as viruses would =
still bring down the whole thing, and in addition to the pcs not =
working, the phones wouldn't work either and it would be total mayhem. =
He says that QOS would make sure that the phone calls always go through =
even if the data network is completely dead.
I was also concerned that the VOIP system would mean every call - even =
desk-to-desk would go through the internet and if the T1 to the internet =
goes down, the phones don't work. His answer to that was redundant T1 =
links, and since they are the ISP and the VOIP provider, they will give =
us a reliable network that won't go down. Also all the VOIP equipment on =
their end is redundant.

What else do I have to worry about with VOIP? Is VOIP ready to replace =
PBX yet, or is it too new?

Any help would be appreciated.

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