We have been experiencing cross talking since we have upgraded our CCM to version: 22.214.171.12400-4 two months ago. I know cross talking has probably nothing to do with the CCM but I just try to give you some detail about the latest changes. It only happens when we call outside through PSTN. I opened a ticket with the Carrier but they say there's nothing wrong in their end. The cross talking is only one way. We can hear them but they can't hear us. Please correct me if I am wrong but accroding to me, cross talking is always a physical layer problem. Am I mistaken?
Here're what I have done in order to resolve the issue but no such a luck so far.
1) Two weeks ago a unpluged and pluged back the cable which connects the GW to the Carrier (PSTN). It helped for two days and the issue came back again.
2) I thought maybe the cable is faulty and changed it and again the problem went away for 3 days and came back again.
3) Lastly, I rebooted the gateway and we were good for a week or two but unfortunately it came back again yesterday. I don't know what else I can do. Has anyone experienced such a problem? If so, what have you done to get rid of it?
GW Version 12.4(13r)T
Solved! Go to Solution.
You may want to check your IOS/DSP versions against this bug: CSCsg47594
I would give you more information, but 12.4(13r)T is your rommon version, not IOS.
I noticed that I had some slip errors on the Controler t1. By adding the "network-clock-select 1 t1 0/0/0" I think there would be no slip error anymore. Do you guys think this was the cause of our cross talking issue? How do the dspfarms configuration look like. Do I need to change anything regarding the dsp allocation?
Cross talk is usually the cause of one of two things:
1) This bug
2) Provider mixup on the b-channel.
Your IOS is vulnerable to the bug I listed above. Since you are on 12.4(10), you will want to upgrade to 12.4(13) or later.
The network-clock-select command syncs the DSP TDM clocking up with the provider and ensures that the voice is on the same time domain. This shouldn't cause any signaling or cross talk issues. Common problems from lack of proper clocking are fax failures and small cracks/pops/hisses in the line quality.
Which bug ?
The thing is that OP titled as crosstalk, then mentioned one-way voice. Either way, you start with a clean controller to begin with.
This bug: CSCsg47594
If you have cross talk on a channel, and the channel that the router is getting confused with is inactive, you will have one-way audio.
I think now we are facing the bug that Nick has mentionned. The issue is back and on top of that the conversation breaks up continousley. What is the most recommanded IOS version for my GW that I can Upgrade to? In the mean time, can I use the workaround solution? If so, which one?
If you're not using new features, you can go somewhere in 12.4 mainline, such as 12.4(23).
If you're using SIP, or any other newer features, you would probably want 12.4(15)T8.
We are not using SIP for now but isn't it better that I go with 12.4(15)T8? Could you please tell me if I can use the workaround for now because 80% of calls break up and cross connect. Which workaround would you recommand?
If you want a quick workaround, disabling conferencing should fix the problem. This bug is only around when conferencing is configured on the DSP.
Otherwise 12.4(15)T8 is still a valid workaround.
What will happen to our conference calls?
In order to disable the conferencing, all I need to do is to shutdown the dspfarm profile 20 conference interface, am I mistaken?
Yes, to shut down conferencing just shut down the profile.
But, you conference calls go away.
1) No conferencing, but you can check if you're definitely hitting the bug
2) Upgrade and hope it fixes it.