May 20
    2009

    IP phones with No Media Gateway-One Way Garbled Audio

    Michael Gravallese
    [Subscriber Members]
    We have a small remote office that we want to deploy 5 or 6 phones at, without a Media Gateway. I built a location and a Network Region and put the IP address range of the site in the Network Map. The phones register and we can call them and they can call us. We are using G.711MU codec, for this Network Region. The problem is that the conversation starts out fine, and then after 3 or 4 seconds, the audio becomes very garbled and you cannot even hear the far end. They say they can hear us fine. While on a call, our Packetization delay is about 20ms and the Network Jitter Delay is about the same. The One way Network Delay is only 1 ms. Any idea's??
    Chris Birckhead
    [AvayaUsers.com Moderator]
    How much bandwidth is available between the two offices? This sounds like a classic QOS issue.
    Michael Gravallese
    [Subscriber Members]
    They have a Flex T1 with MPLS on the remote site. I think 8 channles are feeding the POTS lines in that office, so that leaves us a little over 1 Meg for MPLS.
    Chris Birckhead
    [AvayaUsers.com Moderator]
    Ok.. so you're using MPLS... most MPLS services have classes used for Real Time traffic.. which you have to tag and make sure are being honored... also.. its usually done my percentage... most deployments are 20-30% etc.. using G.711 over MPLS is going to cost you well over 100K per call.. you are going to chew through your bandwidth very quickly..

    I would confirm with your MPLS bandwidth provider how QOS is handled for your setup.. and change the phones to G.729... and see if that doesn't help.
    Michael Gravallese
    [Subscriber Members]
    I acutally did change to G.729 and limited the bandwith to 50kbps on communciations to the other Network Reigons, and it did not seem to help, when I call her. I ask her to call me and she cannot connect to me at all, as soon as she goes off hook and I run a list trace on her extension, I am seeing packet loss values in the 30's
    Heath Reynolds
    [Subscriber Members]
    I had this issue with verizon MPLS. I think they have four classes of service on the MPLS with real time queue being GoldCAR. You purchase a set amount of GoldCAR on each endpoint and anyhing over that amount is dropped.

    Our NOC ordered each site with the smallest amount of GoldCAR possible so the first one we added VOIP to all of the EF marked voice stream packets were being dropped as they over-ran the small amount of QOS purchased (8k per link, I think).

    Try setting that network region to mark you voice packets to something other than EF like 0 then see how a call sounds at a time when you have no congestion. If it sounds better then you know it is the MPLS provider dropping packets when you over-run your provisioned QOS.
    Chris Birckhead
    [AvayaUsers.com Moderator]
    It is isanity to run voip over MPLS without knowing what your profile is.. an MPLS cloud is not a dedicated circuit.. you do not own it end to end.

    Before a single phone hits the desk, or one trunk is pinned up.. you must fully understand how your MPLS handles priority tagged traffic.

    Period, end of story.

    Without a local gateway there, you don't even have the option to have the PBX fail over to use local trunks, once you exceed bandwidth.. all you'll get is a "resources unavailable" on the phone when you hit your self imposed cap...

    You might want to take a step back and start fresh on this...
    Michael Gravallese
    [Subscriber Members]
    Appreciate your concern, but they throw nickels around here like they are sewer covers, and due to the economic downturn.... you know the rest.. blah blah blah, The expectations here are if they work in one remote office, then they must be able to work in all remote offices, without spending any additional money, period end of story. The good news is that I did get it to work, but forcing the G.729 Codec for the NR, and then changing the Call Control PHB and Audio PHB both to 30, then I limited the bandwidth to 40kbps on all Inter_region traffic. Sounds great. Thank you all for your help and suggestions.
    Chris Birckhead
    [AvayaUsers.com Moderator]
    30 is usually class 2... changes to your MPLS profile should be free... won't cost you a cent... and 40K is only 2 calls up before you have issues with everyone else...

    Good luck!

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