Static, Crosstalk, Dropped Calls

[glenng3]

We installed a new IP Office 9 system in September. Since then, we've had complaints about static, crosstalk and dropped calls. Usually, the complaint is that the call was dropped. Sometimes the dropped call is accompanied by static or crosstalk or both. Complaints average about 1 call in 70. All calls are inbound, long-distance. Some are from cell phones, some are from land lines and other PBXes. Our reporting software (Xima Chronicall) indicates the calls are dropped by the caller, not by our staff. Our network is not overburdened. The three PRIs that connect us to the local Telco have been checked and seem o.k. We have the clock quality on the IP Office system set to network, and no clock slips are recorded. We unchecked "Allow Direct Media Path" on all our extensions. Some questions:

- Is 1 call in 70 a high ratio of dropped incoming, long-distance calls?
- If not, can you suggest a reliable reference for this determination?
- If so, can you suggest any troubleshooting methods or things to check?

Thanks.

 

[pmcook]

Can you have a cell phone conversation without static, crosstalk and calls dropped? If your PRIs are not generating errors in the system log then you can eliminate them. Are you using IP or digital phones? What model phones? I had this issue with 9508 phones. Turning off automatic gain control from the phone itself helped somewhat. Another thing I did was to use the SD manager tool to compare the SD card file inventory with the Manager inventory. After adding missing files to the SD card and rebooting the problem was resolved. Can't hurt to upgrade to 9.0.5.

 

[Westi]

make sure you have only 1 PRI set to clock from the network otherwise they might get confused.

Joe W.

FHandw, ACSS (SME), ACIS (SME)


ôThis is the end of the world, make sure to buy your T-shirt before it is too late"
Original expression of my daughter

 

[glenng3]

We have the clock quality set to network on the PRI with the highest use. On the others it is set to fallback or unsuitable. We are using mostly 9611 IP phones and some 4620 IP phones. We expect to have some calls dropped due to spotty cellular service, but some of the dropped calls are from landlines and other PBXes. I'm trying to get an idea of how 1 call in 70 measures up to others' experiences. Thanks for the suggestions.

 

[pmcook]

Time to run a Wireshark capture. How are you handling QoS on the LAN side? Is your network segregated? Are you using VLANs? One out of 70 calls is on the high side.

 

[Gunnaro]

Have you tried "upgrading" again? Could be files missing or HW not running properly. 1:70 is an odd number though.

Is it a particular trunk that drops the calls, or completely random?
(Thinking busted PRI card).
You could try moving the PRI card to another base-card, just to eliminate.

Kind regards

Gunnar
______________________________________
Mille viae ducunt homines per saecula Romam

 

[glenng3]

Network tests prior to installation of the new phone system did not indicate we needed QOS, so we are not using QOS. We have about 230 users. The network is split into ten VLANs, two for servers and eight for users. IP Office System Status has occasionally listed Call Quality of Service alarms, but none of those alarms correspond with dropped calls, and all the alarms concern station-to-station internal calls. There are maybe four of these a day on a busy day. I found one of these alarms on a call I had made internally, and I experienced no trouble on the call.

All of the dropped calls come in on the same PRI, but this simply because we don't have enough traffic at this time of year for the first PRI to fill up, so calls don't roll to the other PRI's. Bear in mind that 1:70 is an average. The number varies day to day.

If I do a Wireshark trace, what should I be looking for?

 

[Gunnaro]

If the fault occurs before the internal network, wiresharking will give you nothing. And SSA is not a reliable source for QoS.

Completely random? Also users or VLan?

Kind regards

Gunnar
______________________________________
Mille viae ducunt homines per saecula Romam

 

[glenng3]

We have two call queues on different VLANs, and both groups have reported dropped calls. It does seem completely random. Although some users do not report trouble, I think it is because they can't be bothered. I should probably make sure of that. The users who do report are pretty consistent, and the reporting software backs them up.

 

[pmcook]

Wireshark would indicate dropped packets and excessive retries which could exacerbate any call quality issues. Without knowing your traffic shape you are just guessing. I cannot imagine 230 VoIP users on a network with no QoS. VLANs will isolate the traffic but that does not mean they will prevent switch saturation. I'm leaning towards sporadic saturation.

 

[Gunnaro]

Well, I'm in xmas mode, can't say I get any epiphanies right now.
You need to catch this on Moniror.

Kind regards

Gunnar
______________________________________
Mille viae ducunt homines per saecula Romam