Distortion, call drop issues


For past one month (since I’ve shifted my server on cloud) I’m facing distortion, call drop issues, I’ve troubleshooted it to best of my abilities but still unable to resolve it.

Ive asterisk 11.25 installed on Centos 6.5. I’ve all hard phones (cisco 7940/7960) with different firmware versions.

While troubleshooting I noted that:

  1. If I listen to a recording of a call in which there was issue, mostly there is no distortion in recording.
  2. There is no specific time for distortion/call drop issue, it just happens randomly
  3. If I listen to a call using call barrage feature, sometimes I hear the voice crystal clear while the agent is having distortion in his call.
  4. Issue is for both inbound/outbound calls.
  5. Issue is also observed in local calls (extension to extension)

What possibly could be the issue?
Can the issue be of transcoding? If yes, how can I check
Also how can I check MOS and Jitter in Centos? is there any free application?

The cause is putting Asterisk in the cloud. VoIP needs a low latency, low loss network. That is not generally true of the public internet.

MOS is purely a function of the choice of codec, and is likely to be constant.

You can use tcpdump and wireshark, or you can use the Asterisk rtcp debug command. There is also an Asterisk option to log the jitter at the end of a call.

The reason of putting Asterisk on cloud is that I’m in Pakistan and all my calls are to/from USA. So from Pakistan minimum latency I receive was 245ms. Therefore to resolve latency issue I shifted my server on cloud. now from here to my server, latency is 150ms.

Can you please guide me about the option to log jitter at the end of a call?