Troubleshooting phone call dropping and audio only one way

[synthesis]

Hello. I am administering a Mitel 3300 ICP. It is connected to the PSTN using two PRI connections: one connects to service provider A's network which uses a landline number (inbound calls are received on this line) and the second one connects to service provider B's network which uses a mobile number (outbound calls are made on this line). Some users have been complaining about the phone call dropping in the middle of a call and the occurrence of one way audio. This happens at random times and is not easy to reproduce. I have checked the audit logs and maintenance logs in the Mitel 3300 web interface around the time that the call problem was reported, but have not found anything which could be the cause. Also, the Mitel 3300 ICP indicates that there are no alarms. Could this mean that the problem is not with the Mitel 3300 ICP? How could one troubleshoot these two problems to find out the cause?

[Dogbreath]

If you use one for outbound and one for inbound then the obvious place to start will be - does the affect inbound, outbound or both?
Are these "real" PRIs or do they go into some kind of convertor box?

[VinceWhirlwind]

On the Mitel controller, navigate to the "Voice Quality Statistics" form and identify the problem calls.
The information on this form can tell you a lot about the call, if somebody familiar with IP can interpret it.

[synthesis]

If you use one for outbound and one for inbound then the obvious place to start will be - does the affect inbound, outbound or both?
Are these "real" PRIs or do they go into some kind of convertor box?

Both inbound and outbound are affected. These are real PRIs.

On the Mitel controller, navigate to the "Voice Quality Statistics" form and identify the problem calls.
The information on this form can tell you a lot about the call, if somebody familiar with IP can interpret it.

I checked the Voice Quality Statistics form but it is blank and there are no entries.

[Dogbreath]

You need to enable VQM then. It's on an adjacent form.

[synthesis]

You need to enable VQM then. It's on an adjacent form.

After enabling Voice Quality Monitoring, calls showed up in the Voice Quality Statistics form but upon inspection of the calls, I did not find anything of concern.

However, I found the cause of the calls dropping, while looking at the :Class of Service Options" form. "Call Duration" was set to 6 minutes and "Enable Call Duration Limit on External Calls" was set to "Yes". This caused all calls to drop after 6 minutes. Setting "Enable Call Duration Limit on External Calls" to "No" fixed the problem.

[x-man]

However, I found the cause of the calls dropping, while looking at the :Class of Service Options" form. "Call Duration" was set to 6 minutes and "Enable Call Duration Limit on External Calls" was set to "Yes". This caused all calls to drop after 6 minutes. Setting "Enable Call Duration Limit on External Calls" to "No" fixed the problem.

Watch that with SIP because they are classed as internal calls and setting the above will not affect them. Don't know if this changed with later releases but still the same in Release 8.0 SP1. Found this out after a LOT of wireharking and trouble shooting a similar problem. That setting had been changed to turn it off but made no difference but turning it off for internal solved the problem.