IP Phones and Static

You are witnessing what happens to VOIP when no "Quality of Service" parameters are enforced on the network traffic. The VOIP packets get "squeezed" by the big wad of traffic that your data sync events produce. Latency goes up and the call quality goes to hell.

If you can configure your gear to use a codec that is more efficient, you might get some relief, but you might not. The only real solution is to install gear that will handle VOIP packets at a higher priority. Google the term QoS.

Yes. DON'T USE A HUB!!!!

Always, always always use a switch, not a hub, with VOIP.

Preferably a switch that supports some sort of QOS, preferably diffserv.

There are other factors as well. Simply going from a hub to a switch would help quite a bit.

He also does not state what type of IP cards he has in his intertel system - that does make a big difference as well. The older IPC cards are 10 base-t. Plug those into a non duplex hub, and you start getting collisions.

The newer IPRC cards are 100baset.

In either case, moving from a hub to a switch will likley make enormous strides in fixing the issue.

1) Do not use a hub. Never-ever. 2) establish and use a separate V-LAN for voice traffic. Do not use VLAN 0 3) Use 802.1Q (aka dot-one-que) to tag and prioritize the voice traffic. Yes, this will cause -data- throughput to slow to a crawl when in contention with a lot of voice traffic. Welcome to VOIP. 4) See #1 above. Worth repeating, never use a hub with VOIP 5) if your voip phones include a built-in 2-port switch (so you can plug your PC into the back of the phone) then have your network folks set up network trunking to force the voice call to use the voice VLAN while forcing the data to go over the data VLAN

G.729 VOIP compression sounds like crap (at least to me it does). However, uncompressed VOIP (G.711) consumes considerably more bandwidth than a regular TDM call. VOIP calls can easily consume as much as 84khz per conversation. The advantage of VOIP is that it's bandwidth consumption is dynamic. Any bandwidth not being used for voice is immediately available for data. Most intelligent VOIP phone systems can limit the number of concurrent calls.

Never use a hub.

I could not find on their site if Inter-tel's 8620 phones even have a switch on board, do they? I any case, it would NOT be safe to assume that, even if there is a switch, it is capable of doing VLANs. Quite contrary, for an entry to mid-level model like 8620 (taken from their site, again) it would be better to assume that the switch, if they have it is NOT capable of doing VLANs. The physical port VLAN can still be implemented if you use two separate cables for your desktop and your VoIP phone.

Totally agree.

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Never use VOIP. ;-)

Nothing beats a single POTS pair.

Except when it comes time to build out a "new" office or set up some emergency phones in an eyeblink hurry. VOIP can cut your cabling requirements literally in half & really expedite (and simplify) all future moves & adds. And with the right VOIP pbx there's even a way to do it all and still meet your 9-1-1 requirements.

I've been a pots man myself since the days of 1A2 key systems, but I'm highly interested today in remaining employed (and employable) for the next 7 years until I reach retirement age, so you either accept VOIP and pick up some data networking skills to go with it or else you go to work for the Honey Dippers cleaning septic tanks.

The "power" requirement certainly is one of the drawbacks of VOIP but in time we will come to accept it as the norm. In many corporate enterprise settings total cost of ownership is being looked at more closely than is reliability. If the network goes down (taking the phones with it) more than half of the users will still have their cellular phones, whether they be personal ones or company-furnished. A phone outage today has far less impact than it did 5 years ago. (and network reliability is improving)

Especially that exquisite shocking sensation on touch when it rings! ;-) You just can't get it from VoIP except in a lightning storm. ;-)

wdg@[206.180.145.133] wrote: ....

Not necesarily: my cable has 99vdc so my phone over cable (not VOIP) does not loose the connection even if my 110/220vac transformer is off-line. I do not see why VOIP (when offered by cable company) could not do the same thing. - RM

Power is a big problem. Our digital phone system with maybe 1200 phones takes a few watts per phone, and we have a battery backup and rectifier for them, totaling about 54VDC at 100A, or 5kW. The big old batteries will keep them running for only 15 to 20 minutes when there's a power failure.

When you have a few phones it's not a problem, but when you have a whole neighborhood of thousands, it's a complex and major problem, thousands of watts. We had the telephone lines that we considered essential services, such as fire alarm lines and elevator phones, connected to the central office with hard copper, so that we wouldn't have a reliability problem. We have over a thousand of lines that go thru pair gain equipment, which is backed up with both UPSes and a generator, and which still on occasion have a power reliability problem.

But there's only so much power available, and then the battery or fuel runs out. And in the case of a neighborhood, the phone company doesn't tell you that they don't have good backup for the power in those pair gain boxes so common in neighborhoods. High tech brings complexity, and complexity can bring unreliability.

Our digital phone system supplies a few watts at 54V to each pair, and if the pair is shorted the host clamps the current down to a trickle in a second or so. But for that first second, the shorted pair can draw over a hundred mA, and the bright blue arc that occurs alarms most techs that are working on those lines. They don't like it at all!

\"Watt

Sometimes I think I already do, judging by the amount of dirt, filth, grime, rat turds, spider webs, cockroaches, toxic mold, asbestos, fiberglas, and a myriad of other hazards that I'm up to my elbows in when I'm working in those phone closets and ceilings. :-/

enterprise

I wonder what's happeing back here in Florida. Are the telcos still sending out bills to the owners of houses that are no longer there but just a foundation? If they tried to bill me without so much as an MPOE, I'd send the bill back and tell them to put it where the sun don't shine.

And I have some well irrigated farmland on the shore of a large lake in south Florida that I can let you have at a good price.

ANY phone system, VoIP or traditional requires a lot of administration. VoIP requires different administration than that of a traditional PBX or KSU, but it still requires administration. If you think you can just plug in a new set and walk away, then come talk to me about that farmland.

The terms may change, but the work is still the same - moves, adds, changes, disconnects - it's all the same no matter the phone system.

Can you give an example? - RM