Yikes. I understand the words and most of the concepts but have little practical knowledge to share.
My experience on a small-scale SOHO network is that VOIP is a pretty trivial overhead to the network. As Kevin pointed out, you want to be able to prioritize traffic, as latency and quick response will be much more important to callers (we all take it for granted that two people can carry on a conversation on the phone and interrupt each other. A one-second delay makes that enormously aggravating, and 2 or 3 nearly useless.) As for bandwidth, here's a document with some insight: http://www.cisco.com/c/en/us/support/docs/voice/voice-quality/7934-bwidth-consume.html depending on your choice of compression schemes and codecs, 12 simultaneous conversations would run 240 - 1000 Kbps. That's Kilo, not mega or Giga, so it's pretty unlikely to slow down your database queries. On Tue, Jul 7, 2015 at 4:00 PM, Ken Dibble <[email protected]> wrote: > H folks, > > We are going to replace our existing digital PBX phone system (which has its > own CAT3 wiring). I am desperately seeking objective information on the > issues from people who aren't trying to sell me something. If any of you > have expertise on this topic, perhaps you could answer some questions. > > My knowledge of telephony is virtually nonexistent, and my knowledge of > networking is limited. > > The current PBX system manages about 150 extensions. We would like to go to > at least 200 initially, and perhaps as many as 300-350 later. > > Existing phone and internet service are both currently provided by Level 3 > (formerly TWTelecom). We have fiber coming into the building that carries > both phone and internet service. Somehow, using Adtran and PRI devices, the > bandwidth ascribed to phone vs internet is dynamically managed in response > to demand. However, the internet connection is maximum 25 Mbps down and 5 > Mbps up. The system delivers 12 phone "lines". We also have a fax server > with a Brooktrout fax card that handles 20 incoming DID numbers and two > outgoing (I think "analog") lines, and it has its own Adtran device. > > The computer data network has 4 48-port gigabit switches. They are NOT POE. > > Phone vendors want to sell us a VoIP internal phone system using POE > switches and our current network CAT5 cabling. > > My biggest concern is network throughput and avoiding internal network > congestion. > > The phone sales people have trouble understanding this concern. They don't > seem to be able to distinguish between congestion resulting from use of the > INTERnet as opposed to INTRAnet. > > My network doesn't suffer from network printing, but it is pretty busy. I am > trying to get a straight answer on exactly how much of my internal network > bandwidth a very busy VoIP phone system (at times all 12 "lines" are in > use) will suck up. There are all kinds of advantages to a VoIP system, I > know, but if it slows down the data traffic on the network I am going to be > an unhappy camper. > > I understand that for VoIP to be usable, its packets have to get priority > over other data traveling across the network (otherwise the voices "break > up"). This is what concerns me about the technology. If there are 12 (or > more; growth is inevitable) VoIP conversations taking place at once across > my network, what's going to happen to the responsiveness of the constant > file server access, accounting database access, and internet access (for the > fat-client payroll system and Medicaid billing system) that is also going on > across the network? > > Are there options to add more bandwidth to the network? Affordable options? > For example, are there faster-than-gigabit switches that can use the > existing CAT5 (not 6) cabling? And would it matter, since the computers only > have gigabit network chips? > > Secondarily, if we dispense with the Level 3 Adtran/PRI stuff and go to SIP > networks, am I going to need a lot more INTERnet bandwidth to make that a > reasonable option? > > Any help on this--again, from objective sources not trying to sell me > anything--would be very much appreciated. > > Thanks in advance. > > Ken Dibble > www.stic-cil.org > > [excessive quoting removed by server] _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://mail.leafe.com/mailman/listinfo/profox OT-free version of this list: http://mail.leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/cacw6n4svii5j_-nla2p-1eaub7c_rjs1tzpw8g8ni2wmanu...@mail.gmail.com ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
