SCN Echo problem

[liquidshokk]

Hi All

We have a customer that has 5 sites using SCN. All sites are IP406 except one with IP403 (Annoyingly, as cannot upgrade to latest version) The central site has a 406 with a VCM30 card in it.

All boxes are on 3.2 (61)

Only two of the remote sites were setup for external calls to go out through the central site (currently planning the same for the rest) however one of them is experiencing bad echo on outgoing calls. We have swapped the VCM Card at the affected site then returned and swapped out the 406.

I am startting to believe it is the VCM card at the central site that is the issue, however I do not know enough about the causes of echo to say for sure. Could someone advise?

Also eventually with all remote sites going out through the central site, is this going to cause extreme overloading and cause further problems? or has anyone got a similar working setup? the number of users at each site varies from approx 6 to 60

Many Thanks

 

[kwing112000]

no there does not need to be a line between remote. They will know about each other.

Kevin Wing
ACA- Implement IP Office
Carousel Industries

 

[tlpeter]

Great company who did set this up

different codes and also direct media path on and off on different locations
I guess the do not know how to set up a scn
You ar elucky that they did not make iplines between the remote sites because then you would have a great party (not)


ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
______________
Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[amriddle01]

If you had a direct link between remote sites that would be a mesh topography and that's not supported only star.

ACS - IP Office Implement

 

[ronromano]

Go to system/vcm tab and set to echo return loss to 3 db and reboot, if it gets better but doesn't completely go away go to 0 and reboot.

http://www.nu-tel.com

 

[kwing112000]

I walk into at least 2 or 3 sites a month that are meshed together. It is the first thing i look at and the first thing i fix. I spoke with a sub a couple weeks ago who was having issues with SCN and Vm and he had it all meshed. I told him to remove it and then start troubleshooting it. He didnt and spent 15 hours troubleshooting and still did not fix it. I went in and removed all the lines and rebooted each site and then added 1 line at each remote and all the Vm issues went away....

Kevin Wing
ACA- Implement IP Office
Carousel Industries

 

[liquidshokk]

Yeah, I may have to track down the original company that installed it. kick in the nuts should do it

Regarding the echo cancelation on the vcm tab, I think it was originally on 0 (we upgraded from 3.2.55 to get this feature) and tried changing it to 9 but it made only slight difference.

I have arranged for direct media path to be ticked on ALL sites tonight and for the codec to be set to G.729 on all sites also. One of the sites (not one experiencing echo) did have lines going to 2 of the other remote sites so have arranged to have them removed tonight too...

Tomorrow should be....interesting...

Thanks everyone

 

[liquidshokk]

URGENT!

Since setting direct media path to on for everywhere last night one of the sites is having one way voice... it can hear the other sites but the other sites cannot hear it.

Surely this would happen if it was set one end but not the other?!?!?

what should be my next step as id prefer not to set them all back...

 

[VoiceonData]

i would take them all off and try.

direct media path takes away the IP Office for routing, i have had huge problems with this on

 

[liquidshokk]

wouldnt that put a massive strain on the central site?

 

[VoiceonData]

Allow Direct Media Path: Default = On
This settings controls whether H323 calls must be routed via the H323 gatekeeper (the IP Office) or can be routed alternately if possible within the network structure

 

[liquidshokk]

if the call stays connected through the central site fcor the whole of the call will that not mean that resources at the central site are constantly used i.e VCM channels?

The central site has a VCM3O and i have a feeling that if we turn off direct media path on all sites then this will be used up constantly if my theory is correct?

 

[VoiceonData]

But if the network switches are not set up corrcetly the it can try and route via the switches and end up with issues like one way voice

You didnt have the problem before you turned it on ???

 

[VoiceonData]

No,

How many channels of isdn do you have ?? I assume 30

so you cant make any more external calls than 30


IP Phone to IP Phone will drop the vcm channel when the call is established across the scn


Depends on quanity of users and level of calls

I would take the site you have one way speech and take DMP off at both ends and see if it solves the issue with that site

 

[liquidshokk]

no we didnt but the idea was to have it the same across all sites. some sites had it ticked and others didnt and we had no problems other than echo on a couple of sites. if we turn it off on all sites will this not cause resource issues at the central site? I am going to arrange to have direct media path turned off on all sites tonight

 

[liquidshokk]

there are 60 channels of ISDN at the central site so that wont be a problem. it was VCM channels that I was worried about.

There are not any IP phones actually being used. they are all analogue apart from one site with DS and a Small office.

There is approx 300-400 users across all 5 sites so there could potentially be more than 30 calls going through the central site so I was just a bit worried about the VCM30 at the central site if channels are constantly used when DMP is off.

 

[VoiceonData]

you only currently have two sites using the central site for external calls

I would suggest that its unlikely that you are going to get 30 concurrent calls using the VCM (im assuming that the remote sites are not that big or they would have a local isdn or you would have a 412 with two vcm 30s)

What handset are you using ??

 

[kwing112000]

From the site you were having issues with can you ping to all the other IPO's? is that site on the MPLS? It sounds like something is different with that one site.

Kevin Wing
ACA- Implement IP Office
Carousel Industries

 

[liquidshokk]

Yesterday all sites were set to go through the central site for external calls.

A couple of the sites only have approx 6 users and a couple have around 50

They are using standard BT handsets across the affected sites and the small office site (not experiencing issues)

I have just set all sites to DMP off! Am waiting for customer comfirm outcome...

 

[VoiceonData]

I think im correct in thinking that DMP on comes into play with two IP endpoints

So if you had IP phones at both sites then you could use DMP to release the VCM, but as they are Analogue phones then DMP will not work as the call has to use the VCM to handle the call.

So taking DMP off is the way to go.



I look forward to be shot down in flames

 

[liquidshokk]

changing it to on on all sites caused the problem of one way voice so it definately had an effect on analogue to analogue calls.

They are currently all set to off and i can currently hear any screams so fingers crossed...