Voice distortion in auto and manual calls

[muyousif]

Hi experts, I am running a 120 agents outbound call center dialing at 1.8 ratio. One database + web, three telephony servers. On database server load never goes above 2. Two telephony servers are HP DL380 and one is HP DL360. Normal load is observed on all servers. I am having voice distortion in auto and manual calls, manual calls are made from zoiper directly. Agents and customers complaint about voice distortion. All servers are in local lan, we have direct termination to carrier over PRI in local network. This issue killing me badly and I am unable to understand / solve it. Kindly help me to find out the issue. There is no timing device, is it necessary? also someone suggesting to change Config_HZ from 250 to 1000. I am having hard time to change it by compiling Kernel . An urgent response is highly appreciated.

Vicibox 6.0.3

[williamconley]

1) Welcome to the Party!

2) As you are obviously new here, I have some suggestions to help us all help you:

When you post, please post your entire configuration including (but not limited to) your installation method (7.X.X?) and vicidial version with build (VERSION: 2.X-XXXx ... BUILD: #####-####).

This IS a requirement for posting along with reading the stickies (at the top of each forum) and the manager's manual (available on EFLO.net, both free and paid versions)

You should also post: Asterisk version, telephony hardware (model number is helpful here), cluster information if you have one, and whether any other software is installed in the box. If your installation method is "manual/from scratch" you must post your operating system with version (and the .iso version from which you installed your original operating system) plus a link to the installation instructions you used. If your installation is "Hosted" list the site name of the host.

If this is a "Cloud" or "Virtual" server, please note the technology involved along with the version of that techology (ie: VMware Server Version 2.0.2). If it is not, merely stating the Motherboard model # and CPU would be helpful.

Similar to This:

Vicibox X.X from .iso | Vicidial X.X.X-XXX Build XXXXXX-XXXX | Asterisk X.X.X | Single Server | No Digium/Sangoma Hardware | No Extra Software After Installation | Intel DG35EC | Core2Quad Q6600

3) Timing devices are not necessary, usually, but sound quality is often heavily dependent upon the sound card in the agent's workstation. If you are using different workstations with different sound cards and some have USB and some have IP phones, it's unlikely that "all" would be poor quality, although still possible. If all your agents have the cheapest workstations you could get your hands on, and the cheapest headsets as well, that could certainly be your issue. Get a couple USB headsets to see if you can improve quality.

4) PRI: This is technically defined as "part phone part internet leased connection". But does not specify whether these are PSTN/T1 telephone channels or SIP channels over the internet portion of the PRI. If this is PSTN over T1, all the hardware involved must be checked. The card in the server, any channelbanks involved, the T1/PRI interface box provided ... any/all of them could be the problem.

5) Many call centers with limited bandwidth will use a colocation facility for their Vicidial server and that way only need enough bandwidth to get their agents to the server's location, thus reducing their need for bandwidth (often down to 50% or less). If the problem was with bandwidth, this can remove the problem completely. This costs extra money, if course, since you now are paying for colocation ... but if you do not have fiber or "lots of bandwidth" available, it's often the only viable option. Then the challenge is that you will need to break your lease with the T1 provider, and they are often still just as bad as AT&T in the 70s (will rip you off at every turn, and try to lock you into a contract with systems that don't even work as promised).

4) This is not a "General Discussion". It's a request for support. Moving to the proper board accordingly.

Happy Hunting!

[muyousif]

Thanks William,

Bandwidth is not an issue as we have 100Mb fiber link secondly our interconnection with carrier is over PSTN PRI and servers are located in co location and response time from vicidial servers to those PRI servers is 1 ms. Secondly agent workstations are core i3 and core i5 with multiple vendor head gears. If I listen to live calls or recordings agents voice is always clear but customers complaints they are unable to hear agents. This is very odd case and we are totally unable to separate the issue. In 10000 calls normally 1000 are marked as Voice distortion. Any idea?

VERSION: 2.12-493a
BUILD: 150703-2105

[williamconley]

"Voice distortion" "unable to hear" are totally separate issues. One is usually hardware related or bandwidth related (distortion), unable to hear is usually firewall related.

[muyousif]

I am sorry I am concerned with "voice distortion". It is also observed that distortion is mostly on auto or predictive calls, manual calls have distortion issue in much less percentage as compare to predictive calls. I just want to understand this "is timing device compulsory for 40 - 60 agents on one server HP DL 380 dialing at ratio 1.8 or 2." Secondly Kernel setting Config_HZ=250 does any affect on the performance of call quality?.

[williamconley]

A timing device May improve call quality ... IF the call quality is the result of a problem at the Server and not somewhere else in the data path. You should try a SIP carrier and see if the problem persists.

As for Config_HZ=250, we've NEVER had issues that were resolved by this setting ... but any call quality issues we've had over the years were traced to (a) Agent Sound Cards (b) Agent Poor Bandwidth (lag/jitter) or (c) Bad Carrier. We've never had a call quality issue that was generated by a server. (Ever.)

[muyousif]

Thanks William, issue has been resolved. There was network issue, two network switches were malfunctioning resulted in voice distortion. Thanks again for your kind help and direction.

[williamconley]

Good postback.

But the proper method of saying "thanks" ... is to stick around and answer a few questions. You'd be surprised how many new users can be helped if everyone pitches in.

The more you help = the more advanced users can help with more advanced problems AND more users get helped, and more users enter Vicidial. The project grows and more features get developed. And in the end, you get cool stuff when you Upgrade! *)