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Old 09-02-2012, 06:03 PM
pdgavin pdgavin is offline
Join Date: Aug 2010
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Default Digital Stations Working Great But IP Phones Problems

Rather than dismiss the idea that it may be QoS issues why not use the free and very easy to use tools that are built into the phones and the IP Office. It is very easy to setup and if you set it up in the System/Events tab to email you, you don't even have to do anything except sit back and wait for an email. If you can run it for a week and you are not notified that there was a problem then you can safely eliminate it as a possible cause.

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth". Sherlock Holmes.

QoS Parameters: Release 5.0+.
These parameters are used if Enable RTCP Monitor on Port 5005 is selected (Systems | LAN1 | VoIP). They are used as alarm thresholds for the QoS data collected by the system for calls made by Avaya H.323 phones and for phones using VCM channels. If a monitored call exceeds any of the threshold an alarm is sent to the System Status application. Quality of Service alarms can also be sent from the system using Alarms.
The alarm occurs at the end of a call. If a call is held or parked and then retrieved, an alarm can occur for each segment of the call that exceeded a threshold.
Where a call is between two extensions on the system, it is possible that both extensions will generate an alarm for the call.
An alarm will not be triggered for the QoS parameters recorded during the first 5 seconds of a call.
Round Trip Delay (msec): Default = 350.
Less than 160ms is high quality. Less than 350ms is good quality. Any higher delay will be noticeable by those involved in the call. Note that, depending on the compression codec being used, some delay stems from the signal processing and cannot be removed: G.711 = 40ms, G.723a = 160ms, G.729 = 80ms.
Jitter (msec): Default =20.
Jitter is a measure of the variance in the time for different voice packets in the same call to reach the destination. Excessive jitter will become audible as echo.
Packet Loss (%): Default = 3.0.
Excessive packet loss will be audible as clipped words and may also cause call setup delays.
Round Trip Delay

Good Quality

High Quality

Round Trip Delay

< 350ms

< 160ms


< 20ms

< 20ms

Packet Loss

< 3%

< 1%


Quality of Service Alarms

IP Office 5.0+ supports Quality of Service (QoS) monitoring for IP Office extensions. This is enabled through the Enable RTCP Monitoring on Port 5005 (System | LAN1 | VoIP) setting within the IP Office configuration.
The current quality of service information for a call is displayed within SSA on the extension's Extension Status form. That information is displayed for Avaya H323 IP phones registered with the IP Office. It is also displayed for other extension when they are on a call involving an IP Office VCM channel.
The thresholds for quality of service alarms are set within the IP Office configuration (System | System Events | QoS Parameters). Separate thresholds are set for Round Trip Delay (default 350ms), Jitter (default 20ms) and Packet Loss (0.5%). At the end of a call where any one of the thresholds has been exceeded, the IP Office will output an QoS alarm containing details of the call and the maximum value of each of the QoS measures during the call.

For calls that are held or parked and then resumed, separate QoS alarms may be output for each segment of the call. If the call involves several extension, separate alarms may also be output for each extension.

Is it only a single phone or is it all IP Phones. If it is all IP phones what is the likelyhood that they all went bad at the exact same moment? If they were working fine and all of a sudden they started having problems it is unlikely to be software releated. I suppose it could be the IP Office but then why are the digital phones working okay? It may be the VCM or it may be the lan1 but I haven't heard of those going bad although I suppose it is possible. It is more likely that something changed on the network, like a duplicate IP address or a broadcast storm or a bad nic card causing chatter on the network. If you were going to escalate the case to Avaya Support they would want to have a network diagram and network assement and system monitor traces along with sniffer traces. SSA and IP Office system Event monitoring should be your first step. It is extreemly easy to setup and if it passes at least you can move on to other possible causes before you escalate.

Peter Gavin| Technical Support Engineer|ATAC - IOC|8744 Lucent Blvd. |Rm 446E276 |Avaya - ACA, ACS-M, ACS-I, ACE, ACSS – SME Communications

Last edited by pdgavin; 09-02-2012 at 06:07 PM.
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