Static and clicking during 1800 number conference calls??

[victoriabardy]

Hello All,

We are getting complaints that when people use any conference call service they are getting static and clicking on the calls.  The weird thing is its happening when participants are calling into conference call service numbers that are not hosted out of our location.  I thought it was just the one provider but now it happened with a completely different provider as well, same kind of poor call quality with clicking and static.

We just did an upgrade to 3750X stackwise switches in our access layer, not sure if there could be any issue with the QOS on those switches?  I am just grasping. 

Does anyone here on the forum have any feedback?

Please let me know.

Thank you.

Rgds,

Vicky

[Scott Scheie]

Hi Vicky,

Typically, static and clicking is a result of an analog segment of any call - i.e. - PSTN trunks such as ISDN PRIs, T1s, E1s, POTS lines, etc..  Have you looked at the path your conference calls are taking to get to the conference bridge?  Since you state its happening on 1800 outbound calls, the most likely path your calls would take would be over local PRI trunks. I am taking your statement "It is happening with another provider as well.." to mean another conference bridge provider, not PSTN circuit provider? 

Try performing a debug of the particular voice gateway for your local PSTN trunks to determine the potentially offending circuit.  The best way to start is by using Cisco Dialed Number Analyzer (DNA). 

Go to https://X.X.X.X:8443/dna/showHome.do, where X.X.X.X is the IP of your CUCM Pub.  Go to:"Analysis", "Analyzer" and fill in the appropriate fields to simulate an outgoing call to the TFN of a conference bridge and hit "Do Analysis".   This should direct you to the potentially offending VG/PSTN port.  Try doing a debug on the VG while monitoring and watch your calls go out while you place test calls. Try test calls to other numbers using the same circuit/path and verify you have isolated the source PSTN path.  If you have an alternate PRI, etc. to send test calls out, try sending  your conference calls out the other PSTN path and see if the problem  goes away.

You may need to open a trouble ticket with your PSTN circuit provider to have them correct their issue - this may involve have them performing intrusive testing afterhours.

HTH,

Scott