One way audio issue

[tnestel]

I have an IPO R11 with digital handsets and a PRI. Two numbers are programmed in the ICR to go to the Parts dept (3-4 phones). This group only, and those numbers only, occasionally had one-way audio, maybe 4-6 times a day. Sometimes the caller couldn't hear the employee, and sometimes the employee couldn't hear the caller. It was only on incoming calls. If the caller hung up and dialed again, it always came through the 2nd time.

I was not able to replicate it. I asked the PRI provider to look into some call examples with no result. The issue didn't go away.

The parts department recently moved across town and are now using IP handsets. New phones, new extensions, new group, same ICR and phone numbers. The audio problem followed them over there and now it's worse - up to 50% of their calls. There are no errors or alarms in System Status pointing to an issue.

Any ideas?

 

[Joey Humphrey]

For the IP phones I would make sure that "allow direct media path" on Extension/voip is unchecked for starters. That always caused issues on remote phones. Since its intermittent I would lean more towards the carrier on a PRI call.

 

[tnestel]

Thanks for that tip! I forgot to say that direct media path was checked, and I unchecked it just before posting. The site is monitoring. I don't believe that will resolve the issue completely but it might help and that's good.

 

[ACSscott]

I was going to make the same direct media path suggestion on the IP phones. On the digital phones, not that you need to worry about it anymore, but I was going to say that would have to be the carrier. Probably still the carrier, but you can do some due diligence on your side by using Monitor with filters on. Make sure to include the "Packets" column in the "Call" tab and everything in "RTP Info Monitoring" in the "Media" tab. That will help identify if it's a network / IPO issue. You can also use the Events filters in the "T1" tab and see if it notices anything with the PRI.

 

[derfloh]

If the trunk is PRI and the ignite are digital then there is no IP involved. So neither direct media nor RTP.

Very interesting that it only affects the calls to that group. Or do you just get no feedback from other users who don’t have so many calls?

My guess would also be that it is a carrier issue. Nevertheless… if it really only affects that group, you could use the ISDN L1/2/3 filters and compare what IPO sends to the PRI in case of calls to that group and what it sends in case of all other calls. Maybe you will find a difference and you send something that makes some bad magic at the carrier side. Or if the PRI is a SIP trunk with a PRI converter you send something that does anything with the SIP trunk behind the PRI converter.

Another guess would be that all digital phones that are in the group are connected to the same station card. Maybe the issue moves if you switch some digital ports. Then you know that a card could be defective.

 

[John Tel]

There could be a problem on the PRI with a B channel or multiple B channels where you are seeing the audio issue. Since you mentioned incoming calls, are the calls coming in ascending starting on channel 1 and outgoing descending starting on channel 23? A second “working” call would likely come in on another channel than the first call. This would explain the presence of the issue when they were originally on digital phones and followed to the IP ones. You should be able to use System Status to see the channel the call arrives on and see if you can narrow it down to a channel… just a thought and may not be your issue but I have see this before on PRIs and telco will need to resolve.

 

[tnestel]

I appreciate the suggestions! I have specifically asked if this happens to other users or groups, and they say no.

Another note, if the main operator transfers a call to this group, the call is always good. This ONLY happens when someone calls the DID.

The issue followed the group when they moved from digital handsets to IP. Unchecking Allow Direct Media Path did not help.

I will set up Monitor, post the trace here, engage the company's IT, and contact the carrier. This is beyond my training and I appreciate all of you.

 

[tnestel]

OK, incoming calls use the PRI starting at channel 1. I was able to make the no audio issue happen once, on channel 2, but the next couple of calls to channel 2 worked fine.

I put channel 1 in Maintenance Busy and tried to call channel 3 and the call repeatedly failed. Channels 7-16 have been idle for 19 days. I put channels 1-6 in Maintenance and my incoming calls didn't hit the system at all. No action on Monitor.

I don't know if that tells us anything about the audio issue, but they definitely have a problem with their PRI. I'm calling the provider.

 

[derfloh]

Maybe inky 12 channels booked… 1-6 and 17-22 or similar.

Anyway it sounds more and more like a carrier issue.