NO JOY Poor Voice Quality even on internal calls in building

[Rob Taggart]

 PBX in a Flash GREEN Status Program
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  │  SSH        = ONLINE  | Apache    = ONLINE  | Iptables  = ONLINE    │
  │  Fail2ban  = ONLINE  | Internet  = ONLINE  | Ip6Tables = ONLINE    │
  │  Disk Free  = ADEQUATE| Mem Free  = ADEQUATE| NTPD      = ONLINE    │
  │  SendMail  = ONLINE  | Samba    = OFFLINE | Webmin    = ONLINE    │
  │  Ethernet0  = ONLINE  | Ethernet1 = N/A    | Wlan0    = N/A      │
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  │  PIAF Installed Version  = 2.0.6.4 under *HARDWARE*                │
  │  FreePBX Version          = 2.11.0.37                              │
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  │  Running Asterisk Version = 11.5.1                                  │
  │  Asterisk Source Version  = 11.5.1                                  │
  │  Dahdi Source Version    = 2.7.0.1                                │
  │  Libpri Source Version    = 1.4.12                                  │
  │  IP Address              = 10.1.100.2 on eth0                      │
  │  Operating System        = CentOS release 6.4 (Final)              │
  │  Kernel Version          = 2.6.32-358.6.2.el6.x86_64 - 64 Bit      │
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I am getting complaints about poor voice/?Choppy Voice/Tin sounding calls. I have experienced this myself a few times as well, even on calls from another extension in our building here on the local network. I have a dedicated VLAN setup for phones and the PBX...both are part of the same subnet. I also have QOS enable on the switches and have specified that VLAN 30 (Voice Vlan) be set at 46 class 3. phones and pbx are all gigabit and the network load on the pbx averages about 30 to 40 KBs. I am still very much a VOIP novice and do not know where to start to try and pin down the culprit or where to start...can anyone help?

 

[atsak]

Could the network cable to the server be old / bad or something like that?

I would probably start by removoing all the QoS settings and seeing if there's some sort of unusual reverse problem - typically QoS helps this but it would be interesting to see if the problem got better or worse when you removed it.

 

[randy7376]

Rob Taggart

I have to agree with atsak - take a step back and disable your QoS setup. You're running Gigabit and probably don't need QoS, anyway. That separate VLAN should be sufficient. We run 100Mb Ethernet for both voice and data on the same VLAN and have no issues.

Sometimes, auto-negotiation doesn't quite get things right. Be sure to check your duplex settings between your switch and server and make sure nothing is running at half-duplex. In the past, I've had issues with 3Com switches doing this very thing.

Lastly, you didn't mention what phones you're using. If these are Aastra 6757is, check the firmware version. I'm going by memory now, but somewhere in what I think was the 2.5.x series firmware, there was a complaint of "robot voice". If you have these phones and firmware older than 2.6.x, upgrade!

 

[Rob Taggart]

Thanks,
I have removed all QOS settings from the network....The patch cable is good as well...i am constantly getting 1ms pings to the pbx. Phones are a mix of Snom 870 and 320 on FW 8.7.3.25

 

[gentoobob]

I agree with randy7376 - I've seen were duplex issues happen. Maybe check your interfaces for error or crazy fast flapping. Make sure no one has put a loop into the network. I since it sounds all on an internal LAN codec shouldnt be a problem.