Dropped Incoming External Calls

[mikejobay]

Hi Everyone,

  I'm newbie to this forum,and to the telephony field as well.

I have a small problem and want your advice and expertise on the matter.

We have a customer that has a number of remote offices, and the users in two of these remote offices, are always complaining about intermittent dropped incoming external calls.

This applies only to incoming external calls to the office, where the external callers complain that they can not hear the other end, which

prompts the internal user to end the call, and call again, and after that all is well, they can hear each other with no issues.

Already checked the network connectivity and verified the cabling and all looks good.

Can you please advise where I can further investigate, and what tools to use to debug and collect more data to determine a root cause.

Thanks in advance,

[Joseph Martini]

If the external caller cannot hear the internal IP phone you're looking at a one way audio problem where the internal IP phone's audio isn't getting out to the PSTN caller.  If you're able to reproduce this problem before the internal user hangs up you can bring up the phone's web page by putting the phone's IP address into a browser (make sure the CCMAdmin phone setting, web access is enabled too) and going to Stream 1.  This page will show you where the IP phone is sending it's audio to in the remote address field.  I would then refresh the page a few times to look at the RX and TX counters to make sure that the transmit counters are increasing each time you refresh the page.

Now that you know where the IP phone is transmitting audio to, the next step is to connect to the gateway that audio is going to and running some show commands to check the RTP counters for the call such as "show call active voice brief" multiple times to look for counters incrementing on the gateway.

[mikejobay]

Thanks Joe for the input!

One more thing, could this be a routing issue between our PSTN provider and the external user ISP or somewhere in between, and

should it be reported to them.

Also, if I'm not able to diagnose the issue live when it is happening or reproduce it, is it possible

to use that call sample to check and pull up the logs from the CUCM to analyze the call.

Thanks again!