Latency and Call Quality Issues, Especially in Remote Office

[RichardCoburn]

We have been trying to implement 3CX by working through a reseller for several months. Throughout the process, we have had issues with call quality and latency. After several months of not making progress, we recently purchased 3CX support directly and I have been trying to work through them to resolve our issues for about a week.

Unfortunately, the issue is being escalated by our remote users, and I am concerned that this project will end up being scrapped and we will revert to an analog phone system if I cannot address there concerns on an very fast time table.

As I am not sure on the source of the issue, I have also submitted a support ticket with our SIP provider.

Our implementation is as follows:

SIP Provider: Nexvortex
Codec to SIP Provider: G711u
Software: 3CX Professional
Phones: Cisco SPA525G
Default Phone Codec: G711u
3CX Server Hardware: Dell Optiplex 790, 8gb RAM, i7 2700 processor

Main Office Bandwidth: 50 down/5 up
Main Office User Count: 14
Main Office Internet Gateway: Linksys RV042 with Port Forwarding

Branch Office Bandwidth: 50 Down/5 up
Branch Office User Count: 6
Branch Office Internet Gateway: Sonicwall TZ210
Branch Office Connection Method: 3CX SIP Proxy

Remote Users: 2
Remote User Bandwidth: varies
Remote User Connection Method: Direct

The phones and 3CX server in the main office are all located on a separate dedicated local network. Internet bandwidth at all locations is shared between data and voice communications.

For all internal (extension to extension) calls, we do not experience any issues. This is true for calls within the main office and for calls from the main office to the branch office.

For external to main office calls, we have experienced very few issues, but there have been some issues with call quality.

For external to branch office calls, we regularly experience both lag and call quality issues.

The quality issues experienced by the call participants are not present in the call recordings on the 3CX.

At this point, I am really not certain what the source of the issues is and have little to no idea where to take the troubleshooting from here.

Any help that you can provide would be greatly appreciated.

 

[Nano_Magnus]

Re: Latency and Call Quality Issues, Especially in Remote Of

Hi,

it looks like a network problem to me
between your branch office and your main office.

Are you using VPN to connect main and branch offices?
are you filtering and blocking web and mail access on the branch office?
is your branch office a simple network? or using AD

Excuse my poor English
not my primary language

 

[jpillow]

Re: Latency and Call Quality Issues, Especially in Remote Of

;

 

[RichardCrabb1]

Re: Latency and Call Quality Issues, Especially in Remote Of

Hi,
We have carried out a few quite large installations. It seems to me that most of the problems are related to access for the branch office. To connect remote sites we use routers that support both QOS and VPN. This ensures that voice packets always get priority over data packets. Otherwise mixing data and voice will always lead to quality issues - unless the bandwidth is unlimited. For the number of users that you have I would recommend Draytek 2830 routers. If the Broadband service is still poor at the branch location, then it may be worth adding an additional connection just for voice.

I also note that you have different types of router at each location. It would be much better to make these the same make and model at least, and make sure that QoS is implemented on whatever you use.

It would also be useful to run some ping tests to your SIP provider from all the sites at different times of the day. Pingplotter can help show how delays vary. If the bandwidth is inadequate, then that would help to show this up.

Kind regards
Richard Crabb

 

[lneblett]

Re: Latency and Call Quality Issues, Especially in Remote Of

I tend to agree with the idea of same make routers if for no other reasons than coomanality of setup and troubleshooting.

It sounds like there might be an issue with your main office speeds (10/5). I assume no real issue with internal network speed given the lack of any reported issues, so QoS and VLAN may not solve it, but won't hurt.

My concern is that the server is located in the main building. An incoming call for an extension must come into the main and then be subsequently routed back out to the branch. These calls are also running in conjunction with calls only associated to the main building. I am assuming that your 5mbs connection at the main is essentially doing double duty because it is handling the calls between nexVortex and 3cx and then from 3cx to the phone in the branch and then reversed. I am guessing hat the PBX is providing the audio and I am also assuming that the use of the proxy implies that the branch and main are connected using your 5 Mbps as well and not dedicated and not VPN.

I would expect jitter to be pretty bad depending upon network utilization and especially so on nexvortex calls. Not a nexvortex issue in my mind, but speeds......and especially so not knowing what other Internet and inter office activity might be taking place.

 

[3CXfoxhallsolutions]

Re: Latency and Call Quality Issues, Especially in Remote Of

Just to endorse Richard's comment above ... We too have been using Draytek V2820 & V2830 routers (and even V2955's) - and have found them great at all ends of the network, due to their ability to have an amount of bandwidth set aside for VoIP QoS. They will let the data traffic take all the bandwidth it wants up until a voice call triggers the QoS rule. Then a pre-defined amount of bandwidth is 'clamped' exclusively for the voice traffic.
We normally set up the rule to include TCP/UDP 3CX traffic, and the IP address of the 3CX server. That usually covers all scenarios and enables us to keep pretty good voice quality, even on fairly low speed ADSL.
I believe it's possible to do this with your Sonicwall too ...

best regards

 

[jpillow]

Re: Latency and Call Quality Issues, Especially in Remote Of

I'd look at also going to possibly a symmetrical circuit or just increasing your bandwidth specifically upload, whats your call volume with those 22 users but how much bandwdth (upload mainly) are you getting at the main location (not what you're paying for but actually getting. You may want to look at using the same routers at all location and creating a hub and spoke VPN, I've found hardware VPN's to provide better QoS than SIP Proxy Manger, or direct remote extensions We use the Cisco RV seriers routers mainly for this purpose. Logmein Hamachi VPN by logmein a software vpn that in my opinion provides better QoS than 3cx tunnel. Mind you with that being said I've also clients using 3cx tunnel, direct extension and SPM with no issues whatsoever your going to have to keep testing on your network to determine whats best. Lastly this seems to be very odd as you have a seperate network for voice and data which really in theory should eliviate these issues though they do not. I'd think you'd get better support working directly with a 3cx partner; support at 3cx is great however in your case as you have limited time to work the issue youd most likely get better results and much quicker by letting a partner or someone very familiar with 3cxto handle the issues in conjunction with 3cx support. Good luck and please post what you find out and wha steps you have taken to resolve.

 

[paul1]

Re: Latency and Call Quality Issues, Especially in Remote Of

I had a similar problem with call quality on remote sites. I worked through several issues regarding QoS on the WAN links etc. I think the most significant improvement came from disabling VAD (Voice activity detection) and selecting a fixed jitter buffer size on the phones. I was working with Yealink phones. I don't know if you have the same options on your phones but if you do it would be worth a try to adjust those settings.

Good Luck!
Paul

 

[netswork]

Re: Latency and Call Quality Issues, Especially in Remote Of

Some good suggestions here.

Without a doubt I would recommend a lan to lan VPN between the two sites. I would recommend at both location you segment the voice into its own network. We use fortigates exclusively and they allow you to create the VPN's and apply QOS. You can assign priorities as well as queues.

We use nexvortex in house and on several customer installs. Since your using a voip provider 3cx is going to be delivering the audio to the phone. So voice comes into 3cx from nexvortex and then from 3cx to your remote branch phone.

When you dial extension to extension from branch to branch 3cx sets up the call but is not responsible for delivering the audio...once call setup is done the phones talk directly to each other. What type of switches are you using? QOS on the switches would not be an absolute answer but could help. Ensure your 3cx server is linked to the switch at gig/full duplex. Don't rely on auto negotiation, it should be hard set at the switch. Make sure both of your gateways/routers are hard set on the switch as well. You can do some ping tests from 3cx to the remote branch phones. Look for variances in response time...that is what causes jitter.

Ensure sip ALG is disabled on your routers.