Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Troubleshooting dropped calls - CM 6.0

Hey guys, we use a Call Manager 6 with UCCX setup and we get dropped calls sporadically but I'm not sure the best way to determine the root cause.  I'll look in RTMT to see if there are any alerts and then do a CDR analysis but since it's going through UCCX it's damn near impossible to find the calls.  Anybody got tips for Call Manager troubleshooting?

Cisco Employee

Re: Troubleshooting dropped calls - CM 6.0


The only way one can determine the cause for the dropped call is by collecting traces and opening a case with TAC. In case you plan to open a case with TAC please keep the following information handy.

time of call failure

call flow

calling party and called party number

error message you hear when the call drops




Re: Troubleshooting dropped calls - CM 6.0

Good Evening,

To add to Tapan's suggestions, a few others things that note which TAC will find handy.

1) Are calls dropping after they are delievered to the agents? Meaning the agents are engaged in a conversation with the CU then the call drops. Or are they dropping before. This will help isolate where the call is failing so they know how to route the case.

2) Are you using a PRI, FXO, etc? I would assume the calls are probably coming in via PRI. Do you see any errors on the T1? Include a 'show controller T1'. In my experience most cases with dropped calls typically occur because of issues with telco.

3) I am not sure how often calls are dropping, but from the gateway can you grab 'debug voice cc inout' 'debug asn1 h245' and 'debug isdn q931' if it is a PRI. This will help with diagnosing which end is dropping the call and the cause code.


Super Bronze

Re: Troubleshooting dropped calls - CM 6.0


Best way to look at dropped calls is start with the basics - if you have MGCP gateways, ensure you have detailed logging enabled on the CCMs so that all the backhauled ISDN signalilng is all logged. With that, you can google to get translatorx and/or triplecombo to extract the signalling.

TranslatorX has a nice mode where it can pick out any unusual disconnects (i.e. non 'normal call clearing' ones) and both can pick out the ISDN signalling to show you which end instigates the disconnect. Very useful tools...

If you see the disconnect part of the call originating from the PSTN, then the caller hung up. This may be because they just happened to get fed up as the agent was answering, or it may be that your IVR is unfriendly enough to make them think they weren't getting through.

If it originates in the TX direction, then you probably have an issue internally - but at least you've halved the problem. You'd then need to look further into the logs to try and see why, and may want to enable further debugs on the gateways.


Please rate helpful posts...

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!