3300 - NO Audio Issues

[mrosenberg]

We are having a very strange issue that just reared its ugly head about 3 weeks ago.  About once a day when we make internal (4 digit dial) calls we get what I have been calling the "silent call"  I have experienced this first hand.  I call someone they see me calling they pick up the phone and then silence.  We can't hear each other and the phone still shows the user until we hang up.  It seems like the call is initially setup, but dies when you pick it up.  This is happening intermittently which makes it difficult to troubleshoot.  I have checked the phone stats on the 3300 and don't see any packet loss or anything else out of the ordinary, except very little packets being exchanged for that call. 

We have 6 total sites and an MPLS network with two 3300's and all IP phones.  Our main site has the 3300 and this is centralized.  We have another 3300 in another store that is our secondary element and only comes into play when the primary goes down.  I am able to ping across the network and trace route as well.  We have had this phone network in place now for about 3 months and did not experience this issue until a few week ago. Any help or suggestions would be much appreciated. 

Thanks in advance,

-C

[ralph]

What version of software and controllers are you using?
What model of phones are doing this?

As an experiment, if you can duplicate the issue, put the call on hold and then take off hold.
See if audio then starts.

Ralph

[mrosenberg]

Ralph - Thanks for the response

The software hardware is: 3300 ICP Call Control 40.2.2.7_SP6
The phones that this happens on are 5320's and 5360's. 

I cannot duplicate the issue.  It is random and intermittent.

If it happens again and we put the call on hold then take if off and audio comes back what does that mean? 

[ralph]

It would mean there's something going on with the E2T.  If it's happening IP phone to IP phone then that is probably not the issue.  I'd just like to make sure.

Ralph

[mrosenberg]

Sorry for my ignorance, but what is an E2T and how do I know we even have one?

Thanks

[ralph]

The E2T  stands for 'Ethernet to TDM".
It's what converts IP to allow it to talk to trunks and/or digital or analog devices.

Depending on your controller type, it will be actual hardware or just software.

Ralph

[v2win]

What are the two endpoints or can you describe the call flow

IP phone to PSTN trunk
IP phone to SIP trunk
IP phone to IP phone
IP phone to MPLS to IP phone

[mrosenberg]

IP Phone to IP Phone over an MPLS network.  According to my phone vendors their is nothing in the logs on the 3300 that jumps out at them.  It has happened from all sites not just one site.  Its a head scratch-er.

Thanks for any help you can provide

[v2win]

So IP phone to IP phone there is no e2t involved.

Are there any acl's on the data switches or firewalls involved?

[mrosenberg]

The switches do not have any ACL's that I know of just route statements, we are pretty open from site to site on the firewall as well.  Remember this issue may not happen today, but then happen two times tomorrow.  The same phones that had the issue have been working fine for days now.  This is what is making the issue so difficult to figure out.

[v2win]

Is there a firewall on the MPLS side?

Does it seem to happen after a certain amount of time like 10 minutes then no audio?

In the firewall is there a setting for application layer gateway that can be turned on or off?

[mrosenberg]

I think their may be a firewall on the MPLS (Provider side) It's in their cloud, so they control it.  On my side everything is wide open. 

[jmurray]

We just had this happen today with a 5330 phone.  We have almost 300 5330 IP phones connected to a 3300 controller.  IP to IP internal calls or external calls to one specific phone has no audio.  I can't hear the caller and the caller can't hear me.  I have tried a new phone and that doesn't solve the issue.  I have plugged the phone in a completely different switch and that didn't solve the issue.  Whatever phone I assign this phone extension to has the issue so it seems like it is something associated with this extension in the 3300. 

Any suggestions on what this might be or how to troubleshoot the issue would be appreciated.  Thanks.

Jeff

[ralph]

IP phone to IP phone?
Are all phones on the same subnet?
Is the phone consistently no audio?

Ralph

[jmurray]

All phones are on the same subnet.  It is consistently no audio.  The user made a call this morning and his next call about an hour later had no audio and has been like that all day.  It seems so strange.  I can't be heard and the person called can't hear me.  The only thing I hear is a blip of static every so often otherwise, it is just dead air.  Even when I try to check voicemail, there is just no audio for this extension.  I have pulled the extension to other phones and the problem follows the extension.  I am going to try rebooting the controller tonight to see if that does anything.