VOIP Jitter?

[easiprint]

Looking for some advice. We currently have BT Business Broadband for our business, with speedtest.net showing 6.71mbps download and 0.64mbps upload speeds, which I think should be ok for voip. We use voipfone for our voip, which on the whole is excellent. We have 4 small offices in our building, each with a pc and a cisco IP phone, although usually only 2 of the offices would be used at any one time due to appointments, etc. We have one office however which experiences jitter on the voip phones from time to time. It appears to be bad days, as most of the time it is fine, but then for probably one day a week, just one phone will have problems with jitter. I've put in a QoS router for it and swaped the network cable, but still have the problem.. Is strange that it is only one office with the problem? I've also tried swapping the phone for a different one, but the same office is affected even with a different phone. Anything else I can try. Am I expecting too much for one broadband connection to handle two pc's and two phones at once?

 

[Posilan]

Anything else I can try. Am I expecting too much for one broadband connection to handle two pc's and two phones at once?

You *should* be ok, but it can depend on a number of factors.

Jitter can be caused by high latency - what are the ping times from your LAN to the remote VOIP server? Also check for any packet loss.

Are you doing any other activity on the network when tyhe problem occurs (uploading/downloading large files etc)?

Steve

 

[Dan_Kesher]

We have one office however which experiences jitter on the voip phones from time to time.

Is it only that one office having problems? If so, are the computer and phone sharing one network connection to the router? IE. Is the computer plugged into the phone's pass-through network socket, and then the phone connects to the router?

If the phone and computer share a network connection, next time you have jitter problems, see if the problems are temporarily resolved by disconnecting or switching off the computer.

 

[easiprint]

No downloading or anything else going on.

I have a 30 port network switch, with some QoS ports and some normal ports, so all phones direct to QoS ports and PC's to normal ports. Cables are only 10m so should be ok.

 

[Posilan]

No downloading or anything else going on

There must be something going on thats causing it - what are the ping times when the jitter is happening? Where is your VOIP provider based (country)?

Steve

 

[cjd]

Have you called us and asked for help?

 

[10032012]

So you replaced the router and cable... I am guessing that perhaps its what is between the router and the office phone... (i.e. the cabling and socket) as you say no other offices have the problem.

Are you sure its jitter and not some kind of noise interference? Maybe electromagnetic interference etc.

A 30 port network switch seems a bit ambitious... are you sure that all phone ports have QoS enabled? Is it possible that you enabled QoS on a computer or unused port, and left the line in question without?

 

[John_]

Silly thought really but just wondering if it's possible that scheduled backup or sychronisation going on in the background that you may not be aware of.

 

[Paul_Rosser]

As others have said could be any one of a number of things, could be wiring, high contention rates on your exchange, a faulty ADSL filter, something happening on your network and lots of other things.

You would need to run some tests when the problem occurs to try and narrow it down a bit.

 

[ccsleedsltd]

There must be something going on thats causing it - what are the ping times when the jitter is happening? Where is your VOIP provider based (country)?

Steve

It is in the OP Post..

 

[ccsleedsltd]

As others have said could be any one of a number of things, could be wiring, high contention rates on your exchange, a faulty ADSL filter, something happening on your network and lots of other things.

You would need to run some tests when the problem occurs to try and narrow it down a bit.

I'm afraid most of this is garbage. The OP noted that it only affects one phone of the four in one office which essentially leaves the only options as:

a. Wiring.
b. Switchport (assuming the same port is used)
c. PC Passthru (if in use) saturating the link to the switch
d. Dodgy account by VoIP provider.

 

[Posilan]

It is in the OP Post..

Huh? Where?

Steve

 

[ccsleedsltd]

Huh? Where?

Steve

We use voipfone for our voip,

From the OP..

 

[Posilan]

From the OP..

I missed the provider name, but the ping times would be more relevant and they are (still) missing.

Still, as it's Voipfone - as Colin said earlier in the thread, OP have you contacted them for help? They don't seem to be the sort of company that would knowinlgy see a client have these problems and ignore it.

Steve

 

[cjd]

If you call us - 020 7043 5555 - we'll put a trace on the phone and try to track down the problem. We can't help if we don't know there's a problem.

Given what's been said, the problem is somewhere in the OP's network.

 

[jwoodywoody]

If your 4 office network converges back into one patch panel and switch, you might want to try these 2 things...

For the port on your patch panel that relates to the network point you're having trouble with, replace the patch cable that runs to your switch, and maybe even connect up the replacement patch cable to a different QoS port.

If you still experience the same problem, then you could plug the phone directly into the switch and try to replicate the fault. If the fault subsides when it's plugged directly into the switch, this implies there's a problem with the cabling going from one office back to your patch panel.

 

[RelyOnIT]

If you call us - 020 7043 5555 - we'll put a trace on the phone and try to track down the problem. We can't help if we don't know there's a problem.

Given what's been said, the problem is somewhere in the OP's network.

I've called voipfone for help in the past and they were really helpful