FW: VOIP versus PBX

["Yehuda Goldenberg" <Yehuda () nj essutton com>]

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 tracking.

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] 
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.    How does the vender plan to handle 911 location tracking?
 
2.    The typical PBX has battery backup and, often, emergency generator support, and powers the desktop instruments.  
How does this compare to your network infrastructure?  Is your current phone system considered an emergency 
communication component at your company?  Is your network fully power protected in case of power outages?
 
3.    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.
 
       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 Goldenberg
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 networks.
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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