We are currently wanting to shift all our phones to voip however we have been having issues with lag delays when someone uses the internet in the office.

Currently we have Exetel 512/512, we host our own emails through Ms Exchange, VPN, Remote Desktop services. The other things we do is general surfing of internet, sending emails and downloading files.

At the moment if the internet is idle call quality is perfect and there is no lag time at all. We have a NB5Plus4 which is really ordinary however QOS has been set for outbound UDP as recommended by Netcomm.

The lag occurs really bad when we starting downloading 1 file from the internet. While on the Voip call it takes a very long time for me to hear from the other end. However my voice goes to the other end rather normally.

My question is how do we fix this problem. The lag time hits around 1-2 seconds and makes Voip unusable. Assumming if we started uploading the same would happen ie the person on the other end may take abit of time to hear what I was actually saying.

How do we fix this? Would a better QOS device really help?? Been looking at the Billion range, because we are most likely to go with Asterisk + Soft/Hard SIP Phones with 2 Voip Line Trunks.

Would changing the codec help?
MTU to 576?
or better QOS modem/router?

We will have around 2-3 Voip Lines at the end of the year......?
We use Engin by the way.

anyone got advice?

Yusuke writes...

We are currently wanting to shift all our phones to voip however we have been having issues with lag delays when someone uses the internet in the office.

Use a separate internet feed for VoIP.

S.

Sounds definately like a QOS problem. I do not own a Netcomm and would never buy another so can't help on the modem o(

EDIT:

"1.13. QoS feature controls only the upstream traffic

The QoS feature in this product is only in control of the upstream traffic.

Continuous use of maximum downstream traffic may reduce call quality."

from here:

kb.netcomm.com.au/kb/pri...p?id=1027&Lang=1

Get a better modem/router

You could try a QoS device line the Dlink DI-102

We have had good results with that on shared ADSL lines.

Cheers

Yusuke writes...

How do we fix this? Would a better QOS device really help?? Been looking at the Billion range, because we are most likely to go with Asterisk + Soft/Hard SIP Phones with 2 Voip Line Trunks.

Do you mean 2 incoming PSTN lines or do you mean 2 VoIP lines.

We will have around 2-3 Voip Lines at the end of the year......?
We use Engin by the way.

Using asterisk or something like the Epygi Quadro you wouldonly need the one engin account as you can make mutiple concurrent calls on the one registered account. You would not need 2 - 3 seperate VoIP lines.

The Quadro's have built in QoS. But as ashort term fix a decent QoS device would help on the upstream and probably the overall lag experienced.

Tomcat.

Yusuke writes...

The lag occurs really bad when we starting downloading 1 file from the internet. While on the Voip call it takes a very long time for me to hear from the other end. However my voice goes to the other end rather normally.

As sweetpea says, use a separate line for VoIP.

thanks for all the input!

I didnt know you could make multiple outgoing calls through Engin, I'll try that soon.
Though we do need 2 numbers for people to dial in on, since each number is for seperate services, and it would route to different internal extensions.

The seperate line suggestion would cost a little too much for us, so we are trying best to avoid that.

We had a look at the Dlink device also but because we dont currently have a seperate modem/router, we were thinking more towards a billion router...

does the billion router only QOS Voip well for its internal Voip, we would most likely need PBX functionality thats why Asterisk. Would a billion QOS work well with asterisk?

Is a decent QOS (eg billion) able to help with Downstream also??? Since currently we have Upstream QOS from the NetComm. We haven't really tried uploading and calling though. The only situation we are having is when someone downloads or maybe sending emails, we really dont want those activities to affect the Voip Quality. Lagging makes it unusable.

Yusuke writes...

The lag occurs really bad when we starting downloading 1 file from the internet.

This is the key fact. Your modem/router provides the QoS queuing on outbound traffic, but it's up to the ISPs last hop router to do it on inbound (download) traffic. Unfortunately you'll probably find that Exetel can't dick around with settings on just your line, so there's no real achievable way to do this. That's not an Exetel bash, I don't know any ISP who could/would do this.

One option is to use an ISP that provides a VoIP service and a commitment to prioritise that traffic when it comes to the last hop to your modem. Internode and NodePhone is a good example of this, but NodePhone doesn't have DIDs yet, so not really an option for you.

Another possibility might be redirecting all HTTP traffic to an internal proxy server and then having the proxy rate limit it's downloads. A bit of stuffing around is required here.

Alternately you can sorta-kinda do QoS on your downloads by delaying the ACK packets. You could try using a router that supports this properly (something like m0n0wall on an old PC) and see if it gives you better results.

I was hoping that on the Billion I could do traffic shaping on my own ports and hopefully that will help on download/upload.

ie, I would shape port 80, 21 and the norm ports to like half my bandwidth ie 256, and hopefully this will help voip out, since we aren't going to be using p2p or anything that has huge connection counts...

I've got a new question, the Engin BYO plans.... i think we have a locked plan, we have a SPA 3000, ie voice box 2, which locked. I was trying a softphone today, and figured that I couldn't login the proxy....

am I able to use softphone/asterisk on locked plans?? or do I need to unlock the plan in which I go onto a different server?

Not sure if the quality will be the same, i have strong suspicions the BYO servers wont be as good....