Dealing with Jitter over a WAN

[ErrolDC2]

I am have an issue. (I know, get in line )
I have a user that with a Cisco 7960G behind a 3002 hardware vpn client. We are having one-way voice quality issues when the user calls anyone outside of the company, IE his phone talks to the gateways not another 7960. Packet captures show high deltas inbetween packets - as high as 128ms. Codec is g729. Cisco is basically saying we are on our own on this one (and rightfully so) because the issue is not on the edge, its a network issue that is outside anyones control. Unfortunately, this is not good enough for my boss and he does not want to explore the prospect of getting say a 128K frame relay circuit to this guy's house. So we are exploring upgrading our 1760's to 3745 with NM-HDV2s This way we can increase our DSP capacity to run in high complexity mode. We get less calls per DSP, but we get more buffer per call - about 40-50ms more than we do currrently with flex. But this does not guarantee that the problem will be fixed. So what can I do? I am getting increasingly frustrated because this is out of my control. So now my boss wants me to research a router/NM/VIC/Cross of Christ that has a per call FIFO buffer equal to that of a phone!!?? Can anyone offer some suggestions? QOS is not an issue. Our QOS has already been tested and verified. The problem is the network(s) inbetween me and this fellow trying to use his 7960g.

 

[superiortel]

Same issue with us on a Software based vpn client with IP Communicator and a DT24+ gateway. Inside calls are crispy clear, but calls to the outside always start with a burp and plenty of cut-offs in between. Have you found any solution yet, or is there somebody out there that can suggest a fix ?
The circuit is ok, since we run H323 over Quintums as well and not a single problem....

 

[ErrolDC2]

I'm not sure there is a "fix". Only workarounds. 7960'd have ajitter buffer of about 2s. A gateway running g711 at medium complexity has only about 70ms.That is why phone to phone calls are crystal clear. We are going to upgrade or 1760s to 2800 or 3700 series routers - whatver allows us to stuff the box with dsp's so we can run in high complexity.
What codec are you using? Have you performed any kind of analaysis with a product like ethereal? What is the round trip delay over to the users PC from the edge gateway where the voice gateways are? How variable is that delay? What kind of connectivity does the the user(s) have? Cable, DSL, FIOS?

Errol

 

[superiortel]

I've used Solarwinds. The round trip delay is about 240 ms and the Jitter is about 35 ms. We are using a 192 Kb up / 512 down ADSL on the remote side (South America)
I have coming a router that has given me very good results without breaking the bank, the Cisco IAD2421. I will let you know as soon as I get it up what the outcome is.
For example, we are using these IAD2421's to Mexico with a round trip of up to 160 ms and 80 ms jitter without any service affecting problems (some occasional soft pop, but the circuit in Mexico makes you wonder how VoIP is possible with that packet loss). These are not on a CM, but extending directly, IAD Pri to IAD Fxs in Mexico.