IP Trunking Poor Audio 2

[TrunkMan]

2 Sites linked via IP Trunking(Site A and Site B). This could potentially be a network problem, but I need to eliminate, the fault being the mitel 3300's. The fault I am experiencing is that when Site A calls Site B, the site B phone can hear Site A but not vice versa(95% packet loss). The same applies if Site B establishes a call to Site A. There is no quality of service on the link between the sites, however this used to work in the past without any quality of service. I have been through the IP trunk programming many times now and even compared them to working sites and cannot find any faults. Ive even tried making calls via analogue phone from an ons port off the back AMB board and still get the same result. I have checked all the gateway settings and verified them with the networks team on numerous occassions.

The signalling works fine, just the RTP voice streaming that is getting heavy packet loss.Both sites are behind 1 firewall. Could there be any setting on the 3300 that is misconfigured that will cause this. Anything in network element assignment perhaps ? All calls using G711 and the links bandwidth consumption is very low. Any ideas or suggestions on how I can move forwards on this fault ?

Thanks in Advance.

 

[danramirez]

Do us a favor.

1. Take one IP phone from Site B and register it on Site A PBX. Call some one on site B. What happens to the audio? Can you hear both directions?

Do you know how to configure IP params. manually on an IP Phone?

Most likely you have a network problem, ask the brainy IT guys what they did to the network setup.

Regards,

Daniel Ramirez

 

[kwbMitel]

The likelyhood of this being a network routing issue is in the high 90's percentage wise.

Ping tests can be initiated from the phones directly or from the Maintenance And diagnostics thru the ESM.

Worst case, setup PC's at either end with the same IP config as a phone and do tracert.

Keep in mind that the GW info on the controller IS NOT the GW in use for an IP set to IP set call.

You could try IP set to analog set in either/both directions to confirm the controller's GW.

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Occam's Razor - All things being equal, the simplest solution is the right one.

 

[TrunkMan]

Thank you for your response danramirez and kwbmitel.

Ive now got some good suggestions to try tomorrow when im back on site. Thanks alot guys!

 

[kwbMitel]

To view the network settings on the set and/or access the Debug mode to run tests.

On a live set press and hold both up and down vol keys, release 1 key, type CFG(234), and release the 2nd key.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[TrunkMan]

Ahh yes, and I think also if you view the "ip telephones all" form, it will also mention the phones ip settings when it is in service. When you say "GW info on the controller IS NOT the GW in use for an IP set to IP set call". Doesnt the ip set use the dhcp option 3 for the routing of the packets ? or do the ip devices stream directly to one another ?

 

[kwbMitel]

Yes, the IP Telephones All is a very good tool.

Yes, the Set uses the DHCP option or one statically assigned.

What I meant, and what some people get wrong, is that the Gateway setup in the controller under the Ip Settings for the controller is not used in an IP set to IP set call. The Controller GW setting is only used when setting up the call or when E2T call control is required such as an analog set to IP or VM to IP or PRI to IP or ... to IP.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[kwbMitel]

To quote an example from a recent experience of mine. One of my customers claimed that the Network had not changed but they were having one way audio issues.

I stuck to my guns, so to speak, and the customer was ultimately able to identify an issue on a recently replaced GW where the subnet defined for the routing statement was 255.255.255.0 and needed to be 255.255.252.0. At first glance the statement appeared correct but because the subnet was set incorrectly, the set's packets were being absorbed by the GW.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.

 

[LoopyLou]

kwbMitel:

Am I right in my thinking that once the call is setup between the two sets, the "IP trunking" is really not an issue in that voice streams between the two set IP addresses. I was dinking around with wireshark capturing some traces on my site and it only shows traffic between source Set A and destination Set B ( and visa versa ).

 

[SXWizard]

You are right in your thinking. Once the call is answered the UDP packets are from set to set.

 

[IrwinMFletcher]

Where do you get the 95% packet drop statistic from? Is that just an estimate, or something reporting it? The reason I ask is that if it was a firewall issue, it would be 100%.

 

[scoopdumpster]

If you have one way audio, then you can be assured that the issue is an ACL on a router somewhere blocking udp packets in one direction.

 

[TrunkMan]

Thanks for the responses guys, but managed to get this fixed today. One of the networks guys resolved the fault but didnt say what it was. Its difficult when the fault bounces between networks and voice engineers.

 

[kwbMitel]

They hate it when we're right. In my experience only people with confidence admit their mistakes. Your "Network Guy" is obviously embarrassed.

*******************************************************
Occam's Razor - All things being equal, the simplest solution is the right one.